Sweet Potato Casserole with Homemade Marshmallow | Food Town

Ingredients

• 4 tbsp. (1/2 stick) unsalted butter, melted, plus more for baking dish
• 4 lb. sweet potatoes
• 2 tbsp. dark brown sugar
• 1/4 tsp. freshly grated nutmeg
• 1/8 tsp. cayenne pepper
• 3 large eggs plus 4 large egg whites
• 1 1/2 tsp. pure vanilla extract, divided
• Kosher salt and freshly ground black pepper
• 2/3 c. granulated sugar
• 1/2 tsp. cream of tartar