This is the version of sweet potato casserole I grew up eating, the one my grandmother always made, with a thick layer of toasted marshmallows on top that everyone fought over at the holiday table. While I love my pecan-topped version for a slightly more grown-up take, there’s something about this classic marshmallow-topped casserole that instantly makes a holiday table feel complete. It’s the one recipe I won’t let anyone talk me out of making, year after year.
This Sweet Potato Casserole with Marshmallows features a silky, buttery sweet potato base topped with a golden, toasted layer of marshmallows, just like the classic holiday side everyone grew up with. If you love sweet potato dishes as much as I do, it sits alongside other favorites like my Southern Sweet Potato Casserole with its pecan streusel topping, my simpler Honey Roasted Sweet Potatoes for weeknights, and my Garlic Parmesan Roasted Potatoes for something savory on the same table.
Why This Recipe Works
Mashing the sweet potatoes while they’re still warm gives the filling its silky, smooth texture — cold sweet potatoes never mash as easily or evenly. Adding butter, brown sugar, and a touch of vanilla to the base brings out the natural sweetness of the potatoes without needing to pile on extra sugar, similar to the approach used in a streusel-topped version of this same dish.
Adding the marshmallows during the last several minutes of baking, rather than from the start, is what keeps them from melting into a flat, hardened layer — that timing gives you puffed, toasted marshmallows with a golden top instead of a sunken, sticky mess. Broiling briefly at the end adds that classic toasted color if you want it a little more golden brown.
Ingredients You’ll Need
- 4 cups mashed sweet potatoes (about 4 large sweet potatoes, boiled or baked until soft)
- ½ cup granulated sugar
- ½ cup whole milk
- ½ cup unsalted butter, melted
- 2 large eggs, lightly beaten
- 1 teaspoon vanilla extract
- ½ teaspoon ground cinnamon
- ¼ teaspoon salt
- 3 cups mini marshmallows
Step-by-Step Instructions
1. Cook and Mash the Sweet Potatoes
Peel and cube the sweet potatoes, then boil in salted water for about 15–20 minutes, until fork-tender. Drain well and mash while still warm until mostly smooth.
2. Make the Filling
Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish. To the warm mashed sweet potatoes, add the sugar, milk, melted butter, beaten eggs, vanilla, cinnamon, and salt. Stir until fully combined and smooth. Spread the mixture evenly into the prepared baking dish.
3. Bake
Bake for 25 minutes, until the filling is set but still soft.
4. Add the Marshmallows
Remove the casserole from the oven and sprinkle the mini marshmallows evenly over the top.
5. Finish Baking
Return to the oven and bake for another 8–10 minutes, until the marshmallows are puffed and lightly golden. For extra color, switch the oven to broil for the last 1–2 minutes, watching closely so they don’t burn.
Tips From My Kitchen
- Mash the sweet potatoes while they’re still hot for the smoothest, silkiest filling.
- Add the marshmallows near the end of baking so they toast instead of melting flat.
- Watch closely if broiling at the end — marshmallows can go from perfectly golden to burnt very quickly.
- This casserole can be assembled a day ahead — just add the marshmallows right before baking so they stay puffed.
Nutrition Information
Estimated values per serving, based on 10 servings:
- Calories: approximately 280–310
- Protein: 3–4g
- Carbohydrates: 42–46g
- Fat: 11–13g
- Sugar: 30–33g
For a lighter version, reduce the sugar in the filling slightly and use a lighter hand with the marshmallow topping — you’ll still get that classic look with a bit less overall sweetness.
Storage and Reheating
Store leftovers covered in the fridge for up to 4 days. Reheat individual portions in the oven at a moderate temperature until warmed through — a microwave works too, though the marshmallow topping won’t stay as toasted. This casserole doesn’t freeze particularly well once the marshmallows are added, since their texture changes significantly after thawing, so it’s best enjoyed fresh or within a few days.
Frequently Asked Questions
Can I use large marshmallows instead of mini?
Yes, large marshmallows work too — you may want to cut them in half so they toast more evenly and cover the surface more completely.
Can I make this ahead of the holiday?
Yes, prepare the sweet potato filling and store it covered in the fridge up to a day ahead. Add the marshmallows and finish baking just before serving so they stay fresh and puffed.
Can I use canned sweet potatoes?
Yes, canned sweet potatoes or yams work in a pinch — just drain them well and mash thoroughly before proceeding with the recipe.
Why did my marshmallows melt flat instead of staying puffed?
This usually happens if the marshmallows are added too early or baked for too long. Add them during the last several minutes of baking only, watching closely so they toast without fully melting down.
Final Thoughts
This Sweet Potato Casserole with Marshmallows will always be the version that feels most like home to me, the one that brings back memories of my grandmother’s holiday table every single time I make it. It’s sweet, nostalgic, and the kind of dish that just isn’t a proper holiday spread without it. I hope it earns a permanent spot on your table too.
