Sweet Potato Casserole with Marshmallows and Pecans

Sweet potato casserole with marshmallows is the kind of holiday side dish that earns a place on the Thanksgiving table year after year. The filling is soft and creamy, the pecan layer brings a salty-sweet crunch, and the mini marshmallows bake into a golden, toasty finish. Every bite has a little contrast instead of the one-note sweetness that can make some versions feel bland or overly sugary.

This recipe is built for a holiday crowd, with 12 servings from a 9 by 13-inch baking dish. It has also reached more than half a million families and gained attention on Pinterest. The finished casserole is bubbly around the edges, warm through the center, and topped with the browned marshmallows that make it especially fun to serve. The recipe card is rated 4.56 from 219 votes, and a reader review specifically praised the pecan layer.

Why You Will Love This Sweet Potato Casserole

This casserole brings together three textures in one dish: mashed sweet potatoes, a crisp pecan crumble, and soft marshmallows with toasted tops. Brown sugar and warm spices give the filling its holiday character, while salt in both the filling and topping keeps the sweetness from taking over. Cinnamon, vanilla extract, and nutmeg round out the flavor without requiring a long ingredient list.

It is also a practical choice for a busy Thanksgiving menu. You can boil and mash the sweet potatoes the day before, or prepare the filling ahead and finish the topping and marshmallows when you are ready to bake. The casserole fits naturally beside classic holiday dishes, and the 12-serving yield makes it easy to bring to a family gathering.

Ingredients

For the sweet potato filling

• 4 large fresh sweet potatoes, peeled and chopped into large chunks
• 1/2 cup unsalted butter
• 1 cup brown sugar
• 1/2 teaspoon salt
• 1/2 teaspoon cinnamon
• 1 teaspoon vanilla extract
• 1/4 teaspoon nutmeg

Cutting the sweet potatoes into chunks helps them cook faster than leaving them whole. They should be large enough to hold together while boiling but small enough to become fork tender.

For the pecan topping

• 4 tablespoons unsalted butter, melted
• 1/3 cup brown sugar
• 2 tablespoons all-purpose flour
• 1/2 teaspoon salt
• 1 1/4 cups finely chopped pecan pieces

The topping combines melted butter, brown sugar, flour, salt, and finely chopped pecans into a crumble that bakes over the mashed filling.

For the marshmallow layer

• 10 ounces mini marshmallows

Instructions

1. Prepare the sweet potatoes. Peel the sweet potatoes and cut them into large chunks. Put the chunks in a large saucepan or pot, cover them with water, and bring the water to a boil.
2. Boil until very tender. Cook the sweet potatoes until they are fork tender and can be pierced easily. They should fall apart easily when they are ready to mash.
3. Make the filling. Drain the sweet potatoes and return them to the saucepan. Add the 1/2 cup of butter, then mash with a potato masher. The heat from the sweet potatoes will melt the butter. Add the brown sugar, salt, cinnamon, vanilla extract, and nutmeg, and mix until the filling is well combined.
4. Mix the pecan topping. In a separate bowl, stir together the melted butter, brown sugar, all-purpose flour, salt, and pecan pieces until combined.
5. Fill the baking dish. Grease a 9 by 13-inch baking dish with cooking spray. Add the sweet potato filling and spread it into an even layer.
6. Add the crumble. Spread the pecan topping evenly over the sweet potatoes.
7. Cover with marshmallows. Arrange the mini marshmallows over the pecan topping in an even layer, covering the entire top of the casserole.
8. Bake. Bake at 350 degrees for 25 to 35 minutes, or until the casserole is bubbly and the marshmallows are golden brown on top. Watch closely toward the end so the marshmallows become toasty and golden without burning.

The goal is a browned marshmallow topping that looks toasted but not scorched. Let the visual cues guide the final minutes: the casserole should be bubbling, and the marshmallows should have the golden-brown tops that make the finished dish so appealing.

Tips for Success

• Cut the potatoes before boiling. Large chunks cook faster than whole sweet potatoes, which is especially helpful when several holiday dishes are competing for your attention.
• Wait for the right texture. “Fork tender” means the sweet potatoes should be easy to pierce and soft enough to fall apart. If they are still firm, they will be harder to mash smoothly.
• Use the potato masher while the potatoes are hot. Add the butter as soon as the drained potatoes return to the saucepan; their heat melts it as you mash.
• Spread both toppings evenly. An even pecan layer followed by an even marshmallow layer gives the whole casserole a consistent finish, rather than leaving bare spots around the edges.
• Stay close during the last few minutes. The marshmallows can move from golden brown to burned quickly, so keep a close eye on the dish near the end of the 25-to-35-minute baking window.

Variations

The signature variation in this sweet potato casserole is the two-part topping. A pecan-only version gives the dish a crunchy finish, but this recipe adds mini marshmallows over the pecans for a second layer of sweetness and a toasted, soft texture. If you have usually preferred sweet potato casserole with only sweet potatoes and pecans, this combination is the reason to try the marshmallow layer.

For the intended balance, prepare the pecan crumble with its brown sugar, butter, flour, salt, and pecans, then cover it with the full marshmallow layer before baking. The recipe is written around that contrast, so keep the listed quantities and even coverage rather than turning it into a different casserole. No additional substitutions are needed to make the holiday version complete.

Storage, Make-Ahead, and Reheating

Store leftover sweet potato casserole in an airtight container in the refrigerator for 4 to 5 days. Reheat leftovers in a 350-degree oven or in the microwave until heated through.

To make the casserole ahead, prepare the sweet potato filling and place it in an airtight container in the refrigerator. When you are ready to bake, put the filling into your greased 9 by 13-inch dish, add the pecan topping, and then add the marshmallows.

For Thanksgiving planning, the sweet potatoes can be boiled and mashed the day before. You can also make the casserole ahead and assemble it the next day. This makes the dish a useful choice when the oven and stovetop are already busy with the rest of the holiday meal.

Serving Suggestions

Serve this casserole as a Thanksgiving or holiday side dish while the topping is warm and golden. The recipe makes 12 servings, so it works well for a family table or a larger holiday gathering. The sweet, soft filling and salty, crunchy pecans complement other classic sides without needing a separate sauce or garnish.

For a traditional Thanksgiving plate, serve it with stuffing, mashed potatoes, gravy, cranberry sauce, glazed carrots, and green bean casserole. It also fits a broader holiday menu alongside cheesy cornflake potatoes, broccoli casserole with Ritz crackers, honey butter skillet corn, baked macaroni and cheese, or a dessert such as pecan pie, pumpkin cream pie, pumpkin cheesecake bars, pumpkin cheese ball, Oreo pie, or pecan cream pie.

Frequently Asked Questions

Can I make sweet potato casserole in advance?

Yes. Make the sweet potato filling and refrigerate it in an airtight container. Before baking, transfer the filling to a greased 9 by 13-inch dish, add the pecan topping and marshmallows, and bake as directed.

How can I save time on Thanksgiving?

Boil and mash the sweet potatoes the day before, or make the casserole ahead so it can be assembled the next day. Both approaches move part of the preparation away from the busiest cooking period.

How do I know when the sweet potatoes are ready to mash?

They are ready when a fork pierces them easily and the pieces fall apart. Drain them, return them to the saucepan, and mash them with the potato masher while they are still hot.

When is the casserole done baking?

After 25 to 35 minutes at 350 degrees, look for a bubbly casserole and marshmallows that are golden brown on top. Watch carefully near the end to get a toasty top without burning it.

How should I store and reheat leftovers?

Keep leftovers in an airtight container in the refrigerator for 4 to 5 days. Reheat them in a 350-degree oven or in the microwave until heated through.

What makes this version different from a pecan-only casserole?

It uses both layers: a crunchy brown sugar pecan topping and 10 ounces of mini marshmallows spread across the top. The pecans add salty crunch, while the marshmallows bake to a soft, golden finish.

Recipe Card Details

The recipe card lists 35 minutes of prep time, 35 minutes of cook time, 1 hour 5 minutes total time, and 12 servings. It lists a rating of 4.56 from 219 votes.

The recipe card lists the following nutrition figures: 418 calories, 61 g carbohydrates, 3 g protein, 20 g fat, 8 g saturated fat, 3 g polyunsaturated fat, 8 g monounsaturated fat, 0.5 g trans fat, 30 mg cholesterol, 263 mg sodium, 340 mg potassium, 3 g fiber, 41 g sugar, 11,047 IU vitamin A, 2 mg vitamin C, 56 mg calcium, and 1 mg iron.

Sweet potato casserole is a classic holiday side that can be prepared ahead, carried to the table in one baking dish, and finished with the combination of pecans and golden marshmallows that makes the recipe memorable.