If Thanksgiving had a most-searched side dish, this would be it. This sweet potato casserole is the classic American version: mashed sweet potatoes whipped with butter, brown sugar and cinnamon, then baked in a 9×13 dish under a crunchy pecan streusel. Prefer the marshmallow version? It is in the variations, same base, same timing, because the marshmallow topping has been part of this dish since 1917, when Angelus Marshmallows commissioned the first printed recipe for mashed sweet potatoes baked with a marshmallow topping.
This is not candied yams. There are no sliced potatoes in syrup here. The sweet potatoes are boiled, mashed smooth, and baked as one creamy casserole, so every spoonful has the same soft texture and the same crisp topping. It takes 60 minutes from start to finish, it can be assembled a day ahead, and it sits happily next to the turkey, the stuffing and the cranberry sauce.
Why You’ll Love This Recipe
- The classic, two ways: pecan streusel for crunch, or marshmallows for the gooey nostalgic version. One base recipe, your family picks the topping.
- Creamy, never watery: the potatoes are boiled, drained well and mashed with just enough milk and butter to stay smooth.
- Make-ahead friendly: assemble it the day before, refrigerate, and bake on Thanksgiving Day.
- Feeds a crowd: one 9×13 casserole, 8 generous servings, and it doubles easily for a big table.
- Oven-friendly timing: it bakes at 375 F, the same temperature as most Thanksgiving sides, so it shares the oven.
Ingredients
- 3 lb (about 1.4 kg) sweet potatoes, peeled and cut into 1-inch chunks
- 1/2 cup (1 stick) unsalted butter, melted, divided
- 1/2 cup packed light brown sugar
- 2 large eggs, lightly beaten
- 1/3 cup milk
- 1 teaspoon vanilla extract
- 1 teaspoon ground cinnamon
- 1/2 teaspoon ground nutmeg
- 1/2 teaspoon salt
For the pecan streusel topping:
- 3/4 cup chopped pecans
- 1/2 cup packed light brown sugar
- 1/3 cup all-purpose flour
- 1/4 cup (4 tablespoons) unsalted butter, melted
- 1/4 teaspoon ground cinnamon
For the marshmallow topping (alternative, instead of the streusel):
- 2 cups miniature marshmallows
Equipment
- Large pot
- 9×13-inch baking dish
- Potato masher or hand mixer
- Large mixing bowl
- Small bowl
Instructions
- Heat the oven and prepare the dish. Heat the oven to 375 F (190 C). Lightly grease a 9×13-inch baking dish with butter.
- Boil the sweet potatoes. Put the sweet potato chunks in a large pot, cover with cold water and add a pinch of salt. Bring to a boil and cook for 20 minutes, until the potatoes are very tender when pierced with a fork. Drain very well and return them to the hot pot for 1 minute so the last steam escapes.
- Make the streusel while the potatoes cook. In a small bowl, stir together the chopped pecans, brown sugar, flour, melted butter and cinnamon until the mixture holds together in damp crumbs. Set aside. If you are using the marshmallow topping instead, skip this step.
- Mash the sweet potatoes. Transfer the drained potatoes to a large bowl. Add the melted butter, brown sugar, eggs, milk, vanilla, cinnamon, nutmeg and salt. Mash with a potato masher or beat with a hand mixer on low speed until smooth, with a few small lumps left for texture. Taste and add a pinch more salt if needed.
- Top and bake. Spread the mashed sweet potatoes evenly in the prepared baking dish. Scatter the pecan streusel over the top. Bake uncovered for 25 minutes, until the filling is hot all the way through and the topping is golden and crisp. For the marshmallow version, bake the casserole plain for 20 minutes, then scatter the marshmallows over the top and bake 5 minutes more, until puffed and lightly golden.
- Rest and serve. Let the casserole rest for 5 minutes before serving so the filling sets and each spoonful holds together. Serve hot.
Tips for the Best Sweet Potato Casserole
- Drain the potatoes really well. Water left in the pot is the main reason a casserole turns runny. Drain, then let the hot potatoes sit in the pot for a minute so the steam escapes.
- Mash while the potatoes are hot. Cold sweet potatoes resist mashing and turn gummy if you overwork them. Mash as soon as they are drained.
- Do not over-sweeten the base. The potatoes are already sweet, and the topping adds sugar. Half a cup of brown sugar in the base is enough, and the cinnamon does the rest.
- Watch the marshmallows. They go from golden to burnt in under a minute. Stay by the oven for the last 5 minutes.
This is the sweet counterpoint on the Thanksgiving table. Our Grandma’s Thanksgiving Stuffing Recipe is the savory anchor next to it, and the two bake at the same oven temperature.
Variations
- Marshmallow topping: bake the casserole plain for 20 minutes, add 2 cups of miniature marshmallows, and bake 5 minutes more until puffed and golden. Same base, same total time.
- Half and half: spread the streusel on one half of the dish and marshmallows on the other, so both camps at the table are happy. Add the marshmallows only for the last 5 minutes.
- No nuts: skip the pecans and use 1/2 cup of rolled oats in the streusel, or use the marshmallow topping instead.
- Bourbon version: add 2 tablespoons of bourbon to the mashed potatoes with the vanilla. The alcohol cooks off, the warmth stays.
- Lighter version: use 1/4 cup of butter in the base and 1/3 cup of brown sugar. The casserole is a little less rich, so bake it 5 minutes longer to set.
- Canned sweet potatoes: drain two 29 oz cans well and mash them the same way. The texture is softer, so reduce the milk to 1/4 cup.
Our candied yams are a different dish, sliced potatoes glazed in syrup. If you want that style instead, try our Candied Yams with Pecan Crumble, and keep this casserole for the mashed, baked version.
Make Ahead and Serving
Assemble the casserole up to 24 hours ahead, without the topping: spread the mashed sweet potatoes in the dish, cover tightly and refrigerate. Add the streusel just before baking, and bake straight from the fridge, adding 10 minutes to the covered time, then uncover for the last 10 minutes so the topping crisps. For the marshmallow version, assemble the base ahead and add the marshmallows only for the last 5 minutes of baking. Serve with roast turkey, stuffing and cranberry sauce.
For the tart note that cuts through the sweetness, our Easy Homemade Classic Cranberry Sauce is the 15-minute sauce that belongs on the same plate.
Storage
Leftovers keep 3 to 4 days in an airtight container in the refrigerator. Reheat individual portions in the microwave, or reheat the whole dish covered with foil at 350 F (175 C) for 20 minutes, adding the topping fresh if it has gone soft. Freeze the unbaked base (without topping) for up to 2 months; thaw overnight in the refrigerator, add the topping, and bake as directed.
FAQ
Can I make sweet potato casserole ahead of time?
Yes. Assemble the mashed base up to 24 hours ahead and refrigerate it covered, without the topping. Add the streusel just before baking, and add 10 minutes to the bake time if it goes in cold.
Pecan streusel or marshmallows, which is the classic?
Both are classic. The marshmallow version dates to a 1917 Angelus Marshmallows recipe, while the pecan streusel is the Southern, praline-style topping. This recipe gives you both, from the same base, so the table can have either or both.
Can I use canned sweet potatoes?
Yes. Drain two 29 oz cans very well and mash them the same way, but reduce the milk to 1/4 cup, because canned potatoes are softer and wetter than fresh ones.
How do I keep it from turning watery?
Drain the boiled potatoes well, let the steam escape for a minute, and do not add extra milk. If the mash still looks loose, bake it 5 minutes longer before adding the topping.
Can I freeze sweet potato casserole?
Yes, freeze the unbaked base without topping for up to 2 months. Thaw overnight in the refrigerator, add the topping, and bake as directed.
What can I serve with sweet potato casserole?
Roast turkey, stuffing, cranberry sauce and green beans. The casserole is the sweet side, so a savory stuffing and a tart cranberry sauce balance it best. Start the meal with our Whipped Ricotta Crostini with Prosciutto and Cranberry, the 25-minute appetizer that opens the same Thanksgiving table.
Sweet Potato Casserole: Creamy Mashed Sweet Potatoes with Pecan Streusel or Marshmallows
Ingredients
Equipment
Method
- Heat the oven and prepare the dish. Heat the oven to 375 F (190 C). Lightly grease a 9×13-inch baking dish with butter.
- Boil the sweet potatoes. Put the sweet potato chunks in a large pot, cover with cold water and add a pinch of salt. Bring to a boil and cook for 20 minutes, until the potatoes are very tender when pierced with a fork. Drain very well and return them to the hot pot for 1 minute so the last steam escapes.
- Make the streusel while the potatoes cook. In a small bowl, stir together the chopped pecans, brown sugar, flour, melted butter and cinnamon until the mixture holds together in damp crumbs. Set aside. If you are using the marshmallow topping instead, skip this step.
- Mash the sweet potatoes. Transfer the drained potatoes to a large bowl. Add the melted butter, brown sugar, eggs, milk, vanilla, cinnamon, nutmeg and salt. Mash with a potato masher or beat with a hand mixer on low speed until smooth, with a few small lumps left for texture. Taste and add a pinch more salt if needed.
- Top and bake. Spread the mashed sweet potatoes evenly in the prepared baking dish. Scatter the pecan streusel over the top. Bake uncovered for 25 minutes, until the filling is hot all the way through and the topping is golden and crisp. For the marshmallow version, bake the casserole plain for 20 minutes, then scatter the marshmallows over the top and bake 5 minutes more, until puffed and lightly golden.
- Rest and serve. Let the casserole rest for 5 minutes before serving so the filling sets and each spoonful holds together. Serve hot.
