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Sweet Potato Casserole with Marshmallows

Sweet potato casserole with marshmallows is baked in a 9x13-inch dish until the filling is set and the marshmallow topping is puffed and golden brown. Sweet potatoes, brown sugar, cinnamon, and vanilla make a smooth, warmly spiced filling.
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Prep Time 15 minutes
Cook Time 50 minutes
resting 10 minutes
Total Time 1 hour 15 minutes
Servings: 10 servings
Course: Side Dish
Cuisine: American
Calories: 320
Ingredients Equipment Method Notes

Ingredients
  

For the sweet potato filling
  • 5 tbsp unsalted butter divided (1 tablespoon softened and 4 tablespoons melted)
  • 3 lb sweet potatoes peeled and cut into 1-inch chunks
  • 8 cup water
  • 0.5 cup light brown sugar packed
  • 0.33 cup whole milk
  • 2 eggs large, lightly beaten
  • 1 tsp vanilla extract
  • 0.5 tsp ground cinnamon
  • 0.5 tsp kosher salt
For the topping
  • 1 bag (10 oz) mini marshmallows

Equipment

  • 1 9x13-inch baking dish

Method
 

Prepare the sweet potato filling
  1. Heat the oven to 350°F.
  2. Grease a 9x13-inch baking dish with 1 tablespoon softened butter.
  3. Put the sweet potatoes and water in a 6-quart pot and bring to a boil over high heat.
  4. Reduce the heat and simmer for 15 to 20 minutes, until the chunks are easily pierced with a fork.
  5. Drain the sweet potatoes well.
  6. Return the sweet potatoes to the pot and mash until smooth.
  7. Stir in the remaining 4 tablespoons melted butter, brown sugar, milk, eggs, vanilla, cinnamon, and salt until combined.
  8. Spread the mixture in the prepared baking dish.
  9. Bake for 20 to 25 minutes, until the center reaches 160°F.
Add the marshmallow topping
  1. Scatter the marshmallows evenly over the casserole.
  2. Bake for 8 to 12 minutes, until puffed and golden brown.
  3. Let the casserole rest for 10 minutes before serving.

Notes

For the smoothest filling, mash the sweet potatoes until no chunks remain. Refrigerate leftovers for 3 to 4 days; freezing is suitable. For a dairy-free swap, use plant-based butter and unsweetened non-dairy milk.