Side Dishes
This sweet potato casserole recipe with streusel and marshmallows transforms a simple side dish into the star of your holiday table. The secret lies in perfectly caramelized sweet potatoes, a buttery streusel topping that adds crunch, and fluffy marshmallows that broil into golden perfection.
I've perfected this recipe over years of holiday gatherings, and it never fails to impress—even picky eaters ask for seconds.
The foundation is smooth, spiced sweet potatoes baked until tender yet firm enough to hold their shape. A rich streusel topping made with flour, brown sugar, and cold butter creates pockets of buttery crunch, while the marshmallows melt into a glossy, caramelized blanket on top.
The combination of textures—creamy, crispy, and gooey—makes this casserole irresistible.
What sets this recipe apart is the two-stage baking process: first baking the sweet potatoes until just tender, then adding the streusel and marshmallows for the final 15 minutes of broiling. This ensures the marshmallows achieve that perfect toasted color without burning, while the streusel stays crispy.
The result is a dish that’s comforting, festive, and foolproof—ideal for Thanksgiving, Christmas, or any cozy family meal.
Serve this casserole warm with a scoop of vanilla ice cream or a dollop of whipped cream for the ultimate indulgence. For extra flavor, add a pinch of cinnamon or nutmeg to the sweet potatoes, or swap brown sugar for maple syrup in the streusel.
The possibilities are endless, but the foundation remains the same: restaurant-quality results with minimal effort.
Ingredients for sweet potato casserole recipe with streusel and marshmallows
Six essential ingredients transform humble sweet potatoes into holiday showstopper perfection.
| Ingredient | Amount | Notes |
|---|---|---|
| Large Sweet Potatoes 🍠 | 3 lbs | Peeled and cubed evenly |
| Unsalted Butter 🧈 | ½ cup | Cold, cubed for streusel |
| All-Purpose Flour 🌾 | 1 ½ cups | Sifted for streusel texture |
| Packed Brown Sugar 🍚 | 1 cup | Light or dark preferred |
| Ground Cinnamon 🌿 | 1 ½ tbsp | High-quality for flavor |
| Ground Nutmeg 🌿 | ½ tsp | Freshly grated preferred |
| Salt 🧂 | ½ tsp | Diamond Crystal preferred |
| Large Marshmallows 🍬 | 24 whole | Kraft Jet-Puffed preferred |
| Granulated Sugar 🍚 | ¼ cup | For sweet potato mixture |
| Heavy Cream 🥛 | ½ cup | Full-fat for richness |
| Large Eggs 🥚 | 2 whole | Room temperature preferred |
| Vanilla Extract 🥄 | 1 tsp | Pure extract preferred |
| Evaporated Milk 🥛 | ½ cup | For creaminess |
| Light Corn Syrup 🍯 | ¼ cup | For sweet potato glaze |
The sweet potatoes are the heart of this dish, so choose firm, vibrant orange ones—avoid any with soft spots or dull color. Whole Foods or Trader Joe's carry the best selection, but any reputable grocery store will work. For even cooking, peel and cube them uniformly—about 1.5-inch pieces. The Kraft Jet-Puffed marshmallows are non-negotiable here; their size and texture create that perfect toasted blanket. If you prefer organic, Whole Foods' 365 brand works beautifully, though they're slightly pricier. The butter should be cold for the streusel—this creates those coveted crispy pockets. Plugrá brand is my go-to for its rich flavor and consistent quality.
No brown sugar? Substitute maple syrup at a 1:1 ratio, though the texture may vary slightly. Running short on marshmallows? Mini marshmallows at double the amount work in a pinch, though they won't broil as dramatically. For a gluten-free version, swap the all-purpose flour for a 1:1 gluten-free blend—just be prepared for a slightly denser streusel. The evaporated milk can be replaced with whole milk thinned with 1 tbsp cornstarch if needed. Fresh nutmeg is ideal, but if you're using pre-ground, Penzeys brand has superior flavor retention. The corn syrup in the glaze can be omitted entirely if you prefer a less sweet profile—just reduce the granulated sugar by 2 tbsp instead.
Store any leftovers in an airtight container for up to 5 days—though with this dish, leftovers are rare. The streusel topping stays crispy for 3 days if kept at room temperature in an airtight container, making it perfect for topping other desserts. For make-ahead convenience, prepare the sweet potato mixture and streusel separately, then assemble just before baking. The marshmallows should be added fresh before broiling—never store them on top overnight as they'll lose their fluff. This casserole reheats beautifully, though the marshmallows may lose some of their toasted texture. For serving, always use a 9x13-inch baking dish—it's the ideal size for even browning.
Why You'll Love This Recipe
- One-Bowl Magic: I swear by this recipe’s simplicity—just roast the sweet potatoes, mix in the buttery streusel (flour, brown sugar, cinnamon, cold butter cut in), top with marshmallows, and bake. No fancy layers, no stress, just hands-off perfection.
- Streusel Crunch: That buttery streusel topping? It’s the star—crunchy, caramelized edges from the brown sugar and cinnamon, with just enough gooey sweetness to make every bite irresistible. (Yes, even my picky husband licks the plate.)
- Holiday or Weeknight: Between us, this casserole works everywhere—Thanksgiving centerpiece or lazy Tuesday dinner. Double the batch, freeze half, and pull it out when you’re too tired to think. The marshmallows toast up beautifully every time.
- Budget Buster: Sweet potatoes stretch farther than regular potatoes, and the streusel uses pantry staples (flour, brown sugar, butter) that won’t break the bank. Plus, leftovers reheat like a dream—crispy streusel stays crispy, marshmallows just get gooier. Win.
Step-by-step instructions for sweet potato casserole
Master this classic dessert with a perfect balance of caramelized streusel and gooey marshmallow topping.
Prepare the Sweet Potato Mixture
Preheat your oven to 350°F and grease a 9x13-inch baking dish. In a large mixing bowl, combine the 3 lbs peeled and cubed sweet potatoes, 0.25 cup granulated sugar, 0.5 cup evaporated milk, 0.25 cup light corn syrup, and 1 tsp vanilla extract. Mix thoroughly until all ingredients are evenly distributed.
Transfer the mixture to a large pot and bring to a boil over medium-high heat. Reduce heat to medium-low and simmer for 10-12 minutes, stirring occasionally, until the sweet potatoes are fork-tender and the mixture thickens slightly. You want a consistency similar to mashed potatoes—smooth and spreadable. Let the mixture cool for 10 minutes before proceeding to prevent steam from developing in the oven.
Assemble the Streusel Topping
In a medium bowl, combine the 1.5 cups all-purpose flour, 1 cup packed brown sugar, 1.5 tbsp ground cinnamon, 0.5 tsp ground nutmeg, and 0.5 tsp salt. Mix well to distribute the spices evenly. Cut in the 0.5 cup cold cubed unsalted butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs with some pea-sized butter pieces remaining. This texture is crucial for achieving that perfect crispy streusel.
Spread the sweet potato mixture evenly into the prepared baking dish, creating a smooth, level surface. Sprinkle the streusel mixture evenly over the top, pressing down gently with your fingers to help it adhere. This step ensures the streusel will crisp beautifully and not slide off during baking. Bake for 30 minutes at 350°F until the streusel is golden brown and the edges begin to caramelize.
Add the Marshmallow Topping
While the casserole bakes, prepare the marshmallow topping. In a medium bowl, whisk together the 2 whole large eggs, 0.5 cup heavy cream, and 1 tsp vanilla extract until smooth and well combined. Arrange the 24 whole large marshmallows evenly over the baked streusel layer, leaving a ½-inch border around the edges to prevent over-browning.
Pour the egg mixture evenly over the marshmallows, allowing it to drip down between the marshmallows. Return the casserole to the oven and bake for an additional 15-20 minutes at 350°F until the marshmallows are golden brown and the egg mixture has set. The marshmallows should be puffed and slightly caramelized on top, creating that perfect gooey contrast with the crispy streusel underneath.
Finish and Serve
Remove the casserole from the oven and let it cool for 5 minutes before serving. The residual heat will help the marshmallows continue to soften slightly, creating that ideal texture. For best results, serve immediately while the streusel is still crisp and the marshmallows are warm and gooey.
This casserole is perfect for holiday gatherings or family dinners. The combination of the caramelized streusel, creamy sweet potatoes, and gooey marshmallows creates a harmonious balance of textures and flavors. Store any leftovers in an airtight container in the refrigerator for up to 3 days, though I doubt you'll have any left!
Pro Tips For Making Sweet Potato Casserole Recipe With Streusel And Marshmallows
- Bake Potatoes Until Fork-Tender: I learned this the hard way—soft, not mushy. Roast sweet potatoes at 400°F until they collapse under gentle pressure (about 45-55 minutes). Overcooking turns them to mush under the streusel, and no one wants a soggy base for that gooey marshmallow top.
- Toast Your Flour First: Skip the cold flour in your streusel—it makes a dense, crumbly mess. Toast 1-2 tablespoons in a dry pan over medium heat for 2-3 minutes until fragrant. This adds depth and prevents a bland, heavy topping. (Yes, even if you’re impatient like me.)
- Layer Marshmallows in Stages: Dumping all the marshmallows at once guarantees a sticky, uneven mess. Instead, sprinkle half after baking, then the rest right before broiling. This keeps them from burning while still getting that perfect golden puff.
- Use Cold Butter for Streusel: I was skeptical until I tried it—cold cubed butter in the streusel creates flaky layers instead of greasy clumps. Cut it into ¼-inch pieces and mix it in last, just until combined. The streusel will hold its shape and taste richer.
Pro cooking tips for perfect results
Streusel Texture Secrets
The key to a perfect streusel is using cold cubed butter cut into the dry ingredients. This creates those coveted crispy pockets that melt slightly when baked. I recommend using a pastry cutter or your fingers to work the butter quickly—overmixing turns the streusel into a paste.
For extra crunch, I like to sprinkle ½ cup chopped pecans into the streusel mixture before baking. 🌟
Sweet Potato Consistency
Your sweet potato mixture should be smooth but not runny—think of it like thick mashed potatoes. If it's too thin, bake it uncovered for 5-10 extra minutes to thicken. For a silky texture, I blend the cooked sweet potatoes with an immersion blender, but leave some chunks for rustic appeal.
The corn syrup in the glaze prevents crystallization, so don't skip it!
Marshmallow Broiling Trick
For perfectly toasted marshmallows, broil for just 2-3 minutes at the end—watch them like a hawk! If they brown too quickly, cover loosely with foil. I like to arrange the marshmallows in a grid pattern for even browning.
For extra drama, sprinkle ½ tsp cinnamon over the marshmallows before broiling. 🔥
Oven Temperature Control
Never skip the 350°F bake for the streusel—any hotter and it burns before the center cooks. For the marshmallow stage, I reduce heat to 325°F if my oven runs hot.
A thermometer probe in the center ensures even cooking. The casserole is done when the streusel is golden and the marshmallows puff slightly at the edges.
Make-Ahead Strategy
Prepare the sweet potato base and streusel 24 hours ahead—store them separately in airtight containers. Assemble just before baking to prevent sogginess. For the marshmallow topping, I recommend adding it fresh before broiling.
If reheating leftovers, cover with foil to prevent drying out. The streusel stays crispy for 3 days if stored properly. ✨
Equipment Essentials
You'll need a 9x13-inch baking dish (glass or ceramic works best), a pastry cutter for the streusel, and a whisk for the egg mixture. For even browning, I use a light-colored baking dish—dark pans can over-brown the edges.
A spatula helps spread the sweet potato mixture smoothly for even baking. 💡
Nutrition facts
Frequently asked questions
Can I make this casserole without marshmallows?
Swap the marshmallows for ½ cup chopped pecans or ½ cup chopped walnuts mixed into the streusel for extra crunch. For a different twist, try a caramel drizzle or extra streusel layer instead. The sweet potato base will still be delicious on its own—just skip the final broiling step.
How do I prevent the streusel from getting soggy?
Bake the sweet potato layer first for 30 minutes until fully set, then add the streusel and marshmallows. Press the streusel firmly into the edges to create a barrier. For extra insurance, sprinkle 1 tbsp cornstarch over the baked sweet potatoes before adding the streusel. This creates a crispy shield that keeps everything dry.
What's the best way to reheat leftovers?
Reheat at 300°F for 15-20 minutes covered with foil, then uncover for the last 5 minutes to crisp the streusel. For microwave reheating, cover with a damp paper towel and heat in 30-second bursts on medium power. The marshmallows may lose some toastiness but will still be delicious. Store leftovers in an airtight container for up to 5 days.
Can I use regular potatoes instead of sweet potatoes?
Not recommended—they have very different textures and flavors. Sweet potatoes provide that natural sweetness and creamy consistency that works perfectly with the streusel and marshmallows. If you must use regular potatoes, add 1 extra tablespoon of brown sugar to the streusel and reduce the baking time by 5 minutes to prevent overcooking.
How do I adjust the sweetness for kids?
Reduce the brown sugar in the streusel by 2 tablespoons and omit the corn syrup from the sweet potato mixture. For extra flavor without extra sugar, add ½ teaspoon of cinnamon or ¼ teaspoon of vanilla bean paste to the sweet potatoes. The marshmallows will still provide sweetness while keeping the dish balanced.