My grandma made the best southern sweet potato casserole with marshmallows and pecans for Thanksgiving. This holiday side dish combines a silky smooth, rich, and buttery filling with a gooey, golden brown marshmallow topping. It takes about an hour of prep time and cook time combined, and you can make it ahead!
Every Thanksgiving, I still remember waiting by the oven for those marshmallows to get just brown enough so we could finally eat. I always thought of sweet potato casserole as a hybrid dish. It’s sweet enough to feel like dessert, but rich and savory enough to pair perfectly with your favorite holiday main dishes.
Why You’ll Love Grandma’s Sweet Potato Casserole
- Velvety Filling: Mashing cooked sweet potatoes with melted butter, brown sugar, and warm spices creates a lump-free, custard-like texture that sets perfectly in the oven.
- Balanced Sweetness: Pure vanilla extract and a splash of milk cut through the natural sugar in the sweet potatoes so that the casserole isn’t overly sweet.
- No Sogginess: I’ll show you how to tell that it’s perfectly baked so that the filling is set and the topping is crisp with no sogginess.
- Make-Ahead: Assemble the casserole up to 2 days in advance, cover and refrigerate, then bake and top with marshmallows when you’re ready to eat.
- 9×13 Pan: Yields 8 generous servings in a 9×13 pan, which makes it easy to transport.
Ingredient & Substitutions Notes
- Sweet Potatoes – You’ll need 4 pounds (roughly 4 to 5 medium-large potatoes). If you’re short on time, substitute two 40-ounce cans of drained and rinsed sweet potatoes or yams.
- Unsalted Butter – Adds richness and contributes to the smooth texture. If using salted butter, reduce the sea salt by half.
- Light Brown Sugar – Adds a traditional caramel-molasses flavor.
- Whole Milk – Cuts through the sweetness of the sweet potatoes, adds moisture, and a smooth, creamy texture.
- Large Eggs – Binds the filling, ensuring that the casserole isn’t runny.
- Vanilla Extract – Rounds out the sweetness and elevates the warm spices.
- Sea Salt – Balances the sugar. Regular table salt works too.
- Chopped Pecans – Add a little crunch and a nutty flavor. Sub with chopped walnuts or leave them out entirely if preferred!
- Mini Marshmallows – Melt down into a crisp and gooey, golden brown topping. Large marshmallows work too; just cut them into quarters before scattering over top.
How to Make Sweet Potato Casserole With Marshmallows
Making sweet potato casserole with marshmallows is a two-part process. First, cook the sweet potatoes and then layer the casserole. Before getting started, preheat your oven to 375ºF, and lightly coat the inside of a 9×13 baking dish with nonstick cooking spray.
Cook the Sweet Potatoes
For this recipe, I just boiled the potatoes. You can also cook sweet potatoes in the Instant Pot.
- Peel and slice the washed sweet potatoes into roughly 1-inch cubes. Add to a stockpot.
- Cover with water, and boil over medium-low heat for 10-15 minutes, ’til fork-tender.
- Drain the water, and add the potatoes to a large mixing bowl.
- Mash the sweet potatoes with a potato masher or whip with a hand mixer.
Mix Up the Filling
- Whisk the softened butter, brown sugar, milk, eggs, vanilla extract, salt, and sweet potatoes in a large mixing bowl until well combined.
- Stir the chopped pecans into the filling.
Layer the Filling and Marshmallow Topping
- Spread the sweet potato filling evenly in the bottom of your baking dish.
- Sprinkle the top with marshmallows and the remaining pecans.
Bake the Casserole
Bake at 375°F for 25 to 30 minutes. Sweet potato casserole is done when the marshmallows are golden brown, the edges are slightly puffed, and the filling is no longer jiggly. Since it has raw eggs, you can also poke it with a meat thermometer to ensure that it has reached a safe 165ºF.
Make-Ahead Instructions for Sweet Potato Casserole
Sweet potato casserole is a great make-ahead recipe. First, mix up the filling, and layer it in your casserole dish, leaving the topping off for now. Cover with plastic wrap and store it in the fridge for 2 days.
Sprinkle the marshmallows and pecans on top when you’re ready to bake and serve. Bake it like normal at 375°F for 25-30 minutes.
Technically, true yams and sweet potatoes are two entirely different root vegetables. However, true yams are rare in U.S. grocery stores, and what is labeled as a “yam” is almost always an orange-fleshed sweet potato. As a rule of thumb, a real yam will never have orange flesh; so yes, canned or fresh “yams” can be substituted to make sweet potato casserole.
Doubling this sweet potato casserole will serve 16 guests. Double all the filling ingredients, and divide the mixture evenly between two 9×13 baking dishes. When baking two 9×13 pans together in one oven, rotate the pans halfway through and add 5 to 10 extra minutes to the total bake time. You can also substitute four 40-ounce cans of drained sweet potatoes for the fresh ones to speed up the prep time.
Leftover sweet potato casserole is best stored covered in plastic wrap or in an airtight container in the fridge for 3-4 days. To reheat your casserole, cover it with aluminum foil, and bake at 375ºF for 5-10 minutes. Remove the foil and let it cook another 5-10 minutes so that the marshmallows can crisp back up.
Yes, you can freeze sweet potato casserole without the topping. Layer the filling in your casserole dish, cover with plastic wrap, and store in the freezer for up to 3 months. Let it thaw out overnight in the refrigerator before adding the marshmallows and pecans on top. Then bake like normal.
What to Serve with Sweet Potato Casserole
Sweet potato casserole is as much of a savory side dish as it is a sweet treat. It pairs well with a variety of holiday main dishes and sides.
- Maple Bourbon Roasted Turkey – My take on the most classic Thanksgiving main course.
- Spiral Baked Ham – Not feeling turkey? Go for a salty glazed ham instead.
- Creamy Mashed Potatoes – Easy to make and so rich and buttery.
- Apple Walnut Bread Stuffing – So much better than the stovetop stuffing from the store!
- Honey Glazed Carrots With Rosemary – Healthy side dish with a sweet honey glaze.
- Grandma’s Homemade Dinner Rolls – Another recipe from Grandma’s recipe box. They’re perfect for soaking up extra sweet potato casserole and holiday gravy.
- Classic Ambrosia Salad – Another traditional side dish that borders on dessert. If you like savory fruit salads, you’ll love my Waldorf salad recipe too!
Mix-Ins & Recipe Variations
Here are a few ways you can switch up your sweet potato casserole.
- Top your casserole with a brown sugar and pecan streusel topping instead of the marshmallows.
- Add a hint of pumpkin pie spice or a pinch of cinnamon and nutmeg for extra flavor.
- Brighten the richness of the sweet potatoes with a teaspoon of orange zest. You can also add a tablespoon of orange juice for even more citrusy flavor.
- Stir 1-2 tablespoons of maple syrup directly into the sweet potato mixture.
- Make it allergen-friendly by replacing the nuts with a nut-free granola or toasted pumpkin seeds.
More Holiday Side Dishes
- Southern Broccoli Cheese Rice Casserole
- Creamy Ritz Chicken Casserole
- Green Bean Casserole for a Crowd
- Cheesy Hash Brown Casserole
- Jiffy Corn Casserole With Cream Cheese and Bacon
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Southern Sweet Potato Casserole With Marshmallows
Equipment
- Chef's Knife for slicing the sweet potatoes
- Vegetable Peeler for peeling
- Hand Mixer optional
Ingredients
Casserole:
- 4 pounds sweet potatoes*
- 1/2 cup unsalted butter softened
- 3/4 cup light brown sugar
- 1/2 cup whole milk
- 2 large eggs
- 1 teaspoon vanilla extract
- 1 teaspoon salt
- 1/4 cup chopped pecans
Topping:
- 2 cups mini marshmallows
- 1/4 cup chopped pecans
Instructions
- Preheat your oven to 375ºF, and lightly coat a 9×13 baking dish with nonstick cooking spray.
- Peel and slice the washed sweet potatoes into roughly 1-inch cubes.
- Add the sweet potatoes to a large stockpot. Cover with water, and boil over medium-low heat for 10-15 minutes, ’til fork-tender.
- Drain the water and add the potatoes to a large mixing bowl.
- Mash the sweet potatoes with a potato masher, or whip up with a hand mixer.
- Add the softened butter, brown sugar, milk, eggs, vanilla extract, and salt to the sweet potatoes in the mixing bowl, whisking until well combined.
- Stir the chopped pecans into the sweet potato mixture.
- Spread the mixture evenly into the prepared baking dish.
- Sprinkle the top with marshmallows and the remaining pecans.
- Bake at 375° F for 25 to 30 minutes, or until the marshmallows are golden brown. Sweet potato casserole is done when the marshmallows are golden brown, the edges are slightly puffed, and the filling is no longer jiggly.*
- Serve while warm, and store any leftovers in the fridge.
Video
Making this for Thanksgiving. I always do but forget the recipe from year to year lol… I always add cinnamon and use canned milk as well. And I never add the marshmallows until the very last… then continue to cook until golden brown (which can be fast). Taste in awesome especially after a day or so in the fridge.
That’s great, Ron! I’m so glad you like it!! Thanks for the awesome feedback.
Got many compliments on this recipe at a friendsgiving! I added a bit of cinnamon too
That sounds great, Kaili! I’m so glad everyone liked it!
I added Canned milk instead of whole milk. Added 1/4 tsp Nutmeg, 1/2 tsp Cloves and 1 tsp cinnamon then everything listed in this recipe. I’m going to let these flavors meld in the refrigerator and tomorrow cook them and add marshmallows then add Mini-Marshmallows put in oven last 10 minutes. I did not put pecans on top.
Can I make this without nuts? I have a guest for Thanksgiving that has an allergy to tree nuts. Thanks!
Lil, yes, you can make this without nuts just fine. Happy Thanksgiving!
So yummy!
It really is! Thanks so much, Alyssa.
Absolutely loved this recipe. Made for Christmas Eve dinner and wish i made a bigger batch. Cant wait to make it again.
That’s awesome, Julie! Thanks for the great feedback.
Can i make the pecans and just put on top and not mixed in? Also. Need to feed 12 ppl. Should i double everything?
Absolutely Delicious!
Thanks, Connie!