Sweet Potato Casserole With Marshmallows and Pecans

Classic sweet potato casserole with creamy spiced base, buttery pecan topping, and gooey marshmallows. A holiday side dish favorite.

Sweet Potato Casserole with marshmallows is one of those dishes that's completely weird if you're not from the South or didn't grow up with it on your Thanksgiving table. It gets served as a side dish, not a dessert, meant to sit right next to the turkey and gravy, which honestly confused me the first time I encountered it. My brain couldn't process why we were eating what tasted like dessert alongside savory dishes.

This casserole became a Southern Thanksgiving staple back in the 1950s and 60s when casseroles were the easiest way to feed large holiday dinners. The marshmallow topping might seem unusual, but it's been part of sweet potato dishes for decades, and in the South it just became the expected way to serve them for the holidays. The mix of creamy, spiced sweet potatoes with a toasted marshmallow top is one of those things people either adore or just don’t get at all.

The first time I tried it, I didn't get the appeal at all. But my kids absolutely love it, so I kept making it and eventually learned to prepare it in a way that I actually like too. The pecans are an ESSENTIAL in my opinion because they add this crunchy, buttery layer that breaks up all the sweetness and gives the dish some actual texture. Without them, it's just too one-note sweet for me to handle as a side dish. But plenty of people skip them if they're not fans, and the casserole still works.

My kids always ask for extra marshmallows with theirs, which means by the time everyone's served, the top is completely picked clean and I'm left with the sweet potato base and pecans. That's honestly my favorite part anyway, so it works out. This is one of the dishes that taught me to appreciate even the most bizarre traditional dishes. Now I actually look forward to making it every Thanksgiving because it's become part of our family tradition, even though I never expected my kids would be the ones turning me into a believer.

Ingredients

Sweet potatoes make this casserole so naturally sweet and creamy, and I love roasting them first because it brings out their flavor way better than boiling. Melted butter and heavy cream make everything rich and smooth, while eggs help the whole thing set up properly so it doesn't turn into mush in the oven.

Brown sugar and vanilla extract deepen all that sweet potato flavor. For the topping, I mix flour, brown sugar, and cold butter into this crumbly streusel that gets golden and crispy, with pecans adding that perfect nutty crunch.

The mini marshmallows on top are what make this casserole feel special because they melt into this golden, gooey layer that tastes like childhood but looks fancy enough for holiday dinner. The contrast between the creamy sweet potato base, crunchy pecan topping, and those soft, caramelized marshmallows is what makes every bite so satisfying.

See the recipe card for exact quantities.

Step-by-step Instructions

This sweet potato casserole with marshmallows is a holiday favorite that combines a creamy, spiced sweet potato base with a buttery pecan topping and gooey toasted marshmallows. It’s rich and comforting, making it a perfect side dish for Thanksgiving or Christmas dinner.

Roast the Sweet Potatoes

Preheat your oven to 400°F (200°C). Wash and dry the sweet potatoes, then pierce them all over with a fork. Place them on a baking sheet and roast for 45–60 minutes, or until they are fork-tender. Let them cool slightly, then peel off the skins and mash the flesh in a large mixing bowl until smooth.

Prepare the Baking Dish

Lower the oven temperature to 350°F (175°C). Lightly butter a 9×13-inch baking dish to keep the casserole from sticking.

Make the Sweet Potato Base

To the mashed sweet potatoes, add the heavy cream, melted butter, eggs, brown sugar, vanilla extract, salt, and nutmeg. Mix everything together until the base is smooth and well blended.

Make the Pecan Topping

In a medium bowl, stir together the flour, brown sugar, and salt. Add the cold cubed butter, then use a pastry cutter or your fingers to work it into the mixture until it looks crumbly, like coarse sand. Stir in the chopped pecans to finish the topping.

Assemble the Casserole

Spread the sweet potato mixture evenly in the prepared baking dish. Sprinkle the pecan topping evenly over the surface.

Bake and Add Marshmallows

Bake uncovered for 20 minutes. Remove the dish from the oven, sprinkle the marshmallows evenly over the top, and return it to the oven. Bake for another 5–10 minutes, until the marshmallows are golden brown and slightly puffed.

Serve

Allow the casserole to cool for a few minutes before serving so the topping sets slightly. Serve warm as a side dish for holiday meals.

Storage

Store any leftovers in an airtight container in the refrigerator for up to 3 days. To reheat, cover with foil and warm in a 350°F oven until heated through, about 15–20 minutes. If you’d like the marshmallows to crisp back up, uncover the dish for the last few minutes of reheating.

Recipe