Sweet potato casserole with marshmallows is an iconic part of many a Thanksgiving spread. My grandma used to serve it in a 1970s-era Pyrex dish, which had a burnt orange color that matched the potatoes. Her casserole was famous for its ratio of one part sweet potato to three or four parts marshmallows.
This recipe has a more balanced ratio, with a thick layer of smooth, lightly spiced sweet potatoes and a delicious scattering of toasted marshmallows. Because the marshmallows are added at the end and baked for 5 to 10 minutes, they get nice and browned on the outside and perfectly gooey inside. In other words, they’re absolute bliss!
Because of their seasonality, sweet potatoes generally make for good fall fare. Serve this classic casserole with other Thanksgiving sides or as a special treat with a Sunday dinner. Be sure to choose the best marshmallows when making this dish; the jumbo ones with a hint of vanilla make all the difference.
Sweet Potato Casserole Ingredients

- Sweet potatoes: Look for large sweet potatoes with firm, unblemished skin. Avoid potatoes with bruises or cracks. Sweet potatoes differ from yams (which have white flesh), so double check the produce before buying.
- Milk: Milk thins the mashed sweet potatoes, giving them a smoother texture. We call for 2% here, but you can use any milk you like, including nondairy milks (just make sure it doesn’t have extra flavors or sweeteners).
- Brown sugar: With its molasses-tinged richness, brown sugar adds a caramel flavor to the casserole.
- Butter: A generous dollop of softened butter mixes with the milk to thin and enrich the mashed sweet potatoes.
- Egg: To make this dish a casserole instead of just plain-old mashed sweet potatoes, use eggs to ensure an even bake with a slightly puffy, stable base.
- Spices: Cinnamon, allspice, nutmeg and salt give this potato casserole the tempting flavors associated with classic fall desserts.
- Vanilla extract: Although sweet potato casserole is more side dish than dessert, it still uses vanilla extract to enhance the flavors—just like a sweet potato pie!
- Marshmallows: The toasty-on-top, gooey-inside marshmallow topping is the signature cap of sweet potato casserole. If you’re making sweet potato casserole for a sentimental crowd, skip it at your own peril!


