Side Dishes
This baked sweet potato casserole recipe with marshmallows delivers the ultimate comfort food experience—creamy roasted sweet potatoes crowned with a golden, crispy marshmallow streusel.
The secret lies in perfectly roasting the sweet potatoes until tender yet firm, then topping them with a buttery streusel that transforms into a caramelized, crackly crust while keeping the marshmallows gooey inside. I’ve perfected this recipe over years of holiday gatherings, where it disappears faster than the mashed potatoes.
The magic happens in two key steps: roasting the sweet potatoes until they’re fork-tender but still hold their shape, and baking the marshmallow topping at high heat for just the right amount of time. Too long, and the marshmallows burn; too short, and they stay sticky.
This version balances crispy edges with a soft, sweet center, making every bite a perfect mix of textures and flavors. The streusel adds a buttery, slightly crunchy contrast that cuts through the richness of the sweet potatoes.
What you’ll end up with is a showstopping side dish that’s creamy, sweet, and irresistibly crispy on top—a crowd-pleaser for Thanksgiving, Christmas dinners, or any night you crave a taste of nostalgia.
The aroma alone will have everyone gathering around the table, and the first bite will have them asking for seconds. This isn’t just a side dish; it’s the centerpiece of any meal.
Serve it warm with roasted turkey, ham, or even as a standalone dessert with a scoop of vanilla ice cream. For extra decadence, sprinkle with toasted pecans or a pinch of cinnamon before baking. Let’s get to the oven—this casserole is worth every minute of wait time.
Ingredients for baked sweet potato casserole recipe with marshmallows
Sweet potatoes, buttery streusel, and gooey marshmallows—this crowd-pleaser needs just 12 ingredients.
| Ingredient | Amount | Notes |
|---|---|---|
| Large Sweet Potatoes 🍠 | 3 whole | Medium size, peeled and cubed |
| Unsalted Butter 🧈 | ½ cup | Cold, cubed for streusel |
| All-Purpose Flour 🌾 | 1 cup | For streusel texture |
| Packed Brown Sugar 🍚 | ¾ cup | Lightly packed |
| Large Marshmallows 🧸 | 24 whole | Mini marshmallows for extra crunch |
| Ground Cinnamon 🍃 | 1 ½ tbsp | For warm sweetness |
| Evaporated Milk 🥛 | 1 can | 12 oz can, full-fat preferred |
| Granulated Sugar 🍬 | ½ cup | For sweet potato mix |
| Salt 🧂 | ½ tsp | Kosher or sea salt |
| Ground Nutmeg 🌿 | ¼ tsp | Freshly grated preferred |
| Pecans 🥜 | ½ cup | Toasted, chopped (optional) |
| Vanilla Extract 🍯 | 1 tsp | Pure vanilla preferred |
Sweet potatoes are the heart of this dish. Orange-fleshed varieties like Beauregard stay creamy when roasted. I grab mine from the produce section at Whole Foods—they’re consistent and sweet. For the marshmallows, Kraft Jet-Puffed or Dandies work best—they hold their shape while still melting perfectly. The pecans? Trader Joe's has the best toasted ones in a bag, already chopped. Skip them if you're short on time, but trust me on the extra crunch.
No evaporated milk? Whole milk plus 1 tbsp powdered milk mimics the richness. Short on pecans? Toasted walnuts or crushed graham crackers add a similar crunch. The streusel gets its magic from cold butter—don't skip chilling it or you'll end up with a gummy mess. For extra decadence, swap half the marshmallows for mini marshmallows—they toast faster and give more surface area for that crispy top layer. The cinnamon should be fresh-ground if possible, but store-bought works in a pinch.
Sweet potatoes keep 3 days in the fridge once peeled—roast them ahead and store covered. The streusel mix stays fresh for 2 weeks in an airtight container. Assemble the casserole up to 1 day ahead and refrigerate, then bake straight from the fridge for even browning. Leftovers? Reheat covered at 350°F for 15 minutes—they taste even better the next day, honestly.
Why You'll Love This Recipe
- One-Pan Magic: I swear by this recipe after burning three casseroles in my first year of cooking. Just peel, slice, and layer—no fancy techniques, no extra bowls. The flour-butter mix binds everything together while you’re still deciding whether to watch the game or the news.
- Caramelized Crunch Perfection: That gooey marshmallow top meets the crispy flour crust? It’s the best of both worlds—like a hug from your grandma’s kitchen. The brown sugar deepens the sweetness while the butter gives it that melt-in-your-mouth richness. (Yes, even my picky husband licks the plate.)
- Holiday or Weeknight Win: Between us, this is my Thanksgiving side and my lazy Sunday dinner. Double the batch, freeze half, and you’ve got a stress-free dessert for Christmas too. Honestly, I’ve served it at potlucks, game days, and even as a breakfast-for-dinner treat—it never disappoints.
- Budget-Friendly Indulgence: Sweet potatoes and marshmallows stretch farther than you’d think. A single bag of those big marshmallows feeds six, and the flour-butter mix costs pennies. Leftovers? Even better—reheat slices in the toaster for a crispy, crave-worthy snack. (My kids call it “dessert for breakfast.”)
Step-by-step instructions for baked sweet potato casserole
Here's how to create that perfect balance of crispy streusel and gooey marshmallow goodness.
Prepare the Sweet Potato Base
Preheat your oven to 375°F. Peel and cube the 3 whole large sweet potatoes into 1-inch pieces. Place them in a large mixing bowl and toss with 0.5 cup granulated sugar, 0.5 tsp salt, 0.25 tsp ground nutmeg, and 1 tsp vanilla extract. Mix until the sweet potatoes are evenly coated.
Transfer the sweet potato mixture to a greased 9x13-inch baking dish. Pour the 1 can evaporated milk evenly over the top and stir gently to combine. The milk will start to soak into the sweet potatoes immediately. Spread the mixture out evenly in the dish, creating a smooth surface.
Bake uncovered for 40-45 minutes until the sweet potatoes are fork-tender and the top begins to look slightly dry. You'll know they're ready when a knife slides in easily with just a little resistance. This step is crucial—undercooked sweet potatoes will make your casserole mushy, while overcooked ones will dry out completely.
Make the Crispy Streusel Topping
While the sweet potatoes bake, prepare the streusel topping in a separate bowl. Cut the 0.5 cup unsalted butter into small cubes and place them in a medium mixing bowl. Add the 1 cup all-purpose flour, 0.75 cup packed brown sugar, 1.5 tbsp ground cinnamon, and 0.5 cup toasted, chopped pecans (if using).
Use a pastry cutter or your fingers to work the butter into the dry ingredients until the mixture resembles coarse crumbs with some pea-sized butter pieces remaining. The texture should be slightly crumbly but still hold together when pressed. If it feels too dry, add 1-2 teaspoons of cold water to help it bind.
Spread the streusel mixture evenly over the baked sweet potatoes, pressing down gently to ensure good contact. This helps create that perfect crispy crown we're after. The streusel should cover the entire surface of the sweet potatoes completely.
Add Marshmallows and Bake to Perfection
Arrange the 24 whole large marshmallows evenly over the streusel topping, leaving just a little space between each one. You want them close enough to touch as they melt and expand. Return the casserole to the oven and bake for an additional 15-20 minutes.
Watch closely during the final baking time. The marshmallows should turn a deep golden brown color, puffing up slightly but not burning. The streusel should be golden brown and crispy around the edges. If you notice any marshmallows browning too quickly, tent the dish with aluminum foil to prevent burning.
Remove from the oven and let the casserole rest for 5 minutes before serving. This resting time allows the marshmallows to set slightly and makes the streusel extra crispy. Serve warm with a scoop of vanilla ice cream or a dollop of whipped cream for the ultimate comfort food experience.
Pro Tips For Making Baked Sweet Potato Casserole Recipe With Marshmallows
- Use 425°F for 20 Minutes First: I learned this the hard way—skipping the initial high-heat bake means soggy potatoes and a mushy topping. Crank your oven to 425°F and bake the sweet potatoes uncovered for 20 minutes before adding the marshmallow layer. This gets them tender without turning to mush when the marshmallows melt.
- Cut Potatoes 1.5 Inches Thick: Thin slices? They’ll dry out. Thick chunks? They’ll stay raw. Aim for 1.5-inch slices—big enough to hold shape but small enough to cook through evenly. If you’re impatient like me, you might be tempted to go thinner, but trust the process.
- Toast Marshmallows in Batches: Don’t just dump them all on top at once. Toast the first layer until golden (about 5 minutes), then add the next batch. This guarantees even browning instead of a sad, half-baked top. And if you’re using mini marshmallows? Double the time—they burn faster than the big ones.
- Mix Dry Ingredients First: I used to melt the butter and sugar together, then add flour, and end up with lumps. Instead, whisk the flour, brown sugar, and a pinch of salt dry first, then cut in the butter. This makes the topping smoother and prevents that gritty texture that ruins the whole dish.
Troubleshooting perfect results
Streusel Too Gummy
The streusel isn't crispy enough? Cold butter is your secret weapon—never skip chilling it before mixing. If it still feels soft after baking, spread the streusel more thinly next time. For extra crunch, add 1 tbsp cornstarch to the streusel mix before baking.
I've also found that baking the streusel alone for 5 minutes before adding marshmallows helps set it properly. 🔥
Marshmallows Burn Quickly
Watch those marshmallows like a hawk—they go from perfect to burnt in seconds! If they're browning too fast, tent the dish with aluminum foil and reduce the oven temperature to 325°F for the final 5-10 minutes.
For even browning, arrange marshmallows in a single layer with ½-inch gaps between them. I like using mini marshmallows—they toast faster and give more surface area for that golden color.
Sweet Potatoes Too Dry
Overbaked sweet potatoes? The milk is your savior—add 2-3 tablespoons of milk to the baking dish before the second bake. For next time, reduce the initial baking time by 5 minutes and check for doneness earlier.
If the top looks dry but the center's still firm, cover with foil and bake 5 more minutes at 350°F. The evaporated milk should keep them creamy while the streusel crisps.
Streusel Won't Stick
Press that streusel down firmly when spreading—it needs good contact with the sweet potatoes. For extra adhesion, lightly brush the baked sweet potatoes with 1 tablespoon melted butter before adding the streusel.
If it still won't stick, chill the streusel mixture for 30 minutes before spreading. The cold butter helps it hold together better when pressed down. 💡
Marshmallows Stay Raw
Undercooked marshmallows? Increase the oven temperature to 375°F for the final bake and watch them closely. For even cooking, arrange marshmallows in a single layer with ¼-inch gaps between them. I've found that using Kraft Jet-Puffed marshmallows gives the best balance of gooeyness and crispiness.
If they're still underdone, broil for 1-2 minutes at the very end (watch like a hawk!).
Casserole Too Sweet
Balance that sweetness with ½ teaspoon cinnamon and ¼ teaspoon nutmeg in the sweet potato mixture. For a tangy contrast, add 1 teaspoon lemon juice to the milk before pouring it over the sweet potatoes.
If it's still too sweet, serve with a dollop of sour cream or a sprinkle of flaky sea salt on top. The streusel's brown sugar should provide enough sweetness—reduce it to ½ cup if needed. 🍃
Nutrition facts
Frequently asked questions
Can I make this casserole ahead of time?
Assemble the casserole up to 1 day ahead and refrigerate it. When ready to bake, let it sit at room temperature for 30 minutes before baking. This actually helps the streusel get extra crispy. For best results, bake it straight from the fridge if you prefer a slower rise to golden perfection.
What's the best way to store leftovers?
Store leftovers in an airtight container for up to 3 days in the fridge. To reheat, cover with foil and warm at 350°F for 15 minutes. The marshmallows will soften but still taste amazing. For extra crispiness, broil for 1-2 minutes at the end.
Can I substitute regular marshmallows?
Yes, but use mini marshmallows for better results—they toast faster and give more surface area for that perfect golden crown. Regular marshmallows work too, but you may need to watch them more closely to prevent burning. Arrange them in a single layer with ½-inch gaps for even browning.
How can I make this version vegan?
Replace the butter with ½ cup vegan butter or coconut oil, use evaporated coconut milk instead of dairy milk, and swap marshmallows for vegan marshmallows. For the streusel, use flaxseed meal to bind the dry ingredients. The texture will be slightly different but still delicious!
Why does my streusel get soggy?
Soggy streusel usually means the sweet potatoes weren't fully baked before adding the topping. Make sure they're fork-tender but not mushy before adding the streusel. Also, chill the streusel mixture for 30 minutes before spreading to help it hold its shape. Press it firmly down for that perfect crispy layer.