Creamy Sweet Potato Casserole with Marshmallow Topping Ingredients For the Sweet Potato Base: 4 large sweet potatoes, peeled and cubed 1/2 cup unsalted butter, melted 1/2 cup brown sugar 1/4 cup heavy cream 2 large eggs, beaten 1 teaspoon vanilla extract 1/2 teaspoon ground cinnamon 1/4 teaspoon nutmeg 1/4 teaspoon salt For the Topping: 1 1/2 cups mini marshmallows 1/2 cup chopped pecans 2 tablespoons brown sugar