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a plain baking dish of dense orange sweet potato custard topped with lightly toasted miniature marshmallows, with one spooned opening showing the set filling
Rachel Kim

Classic Marshmallow Sweet Potato Casserole

A toasted marshmallow top needs a filling sturdy enough to carry it, which is why this version uses roasted sweet potatoes and eggs instead of a loose boiled mash. Brown the butter until it smells nutty, then get it out of the hot pan before the dark flecks turn bitter. The filling should feel like a soft custard after baking, with a clean spoonful underneath that sticky cap. Keep the marshmallows off until the center has finished cooking; trying to warm a cold middle under an already-toasted top is a problem that more foil won't neatly solve.
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Prep Time 25 minutes
Cook Time 1 hour 40 minutes
Total Time 2 hours 5 minutes
Servings: 10
Ingredients Method

Ingredients
  

  • 3 lbs whole sweet potatoes scrubbed
  • 5 tbsp unsalted butter
  • 1/2 cup half-and-half
  • 1/4 cup packed light brown sugar
  • 2 large eggs
  • 1 tsp vanilla extract
  • 3/4 tsp fine salt
  • 1/4 tsp ground nutmeg
  • 2 1/2 cups miniature marshmallows
  • 1 tsp unsalted butter for the dish

Method
 

  1. Heat the oven to 400°F. Pierce the sweet potatoes, place on a lined baking sheet and roast for 50 to 60 minutes until completely soft. Split and scoop out the flesh; reduce the oven to 350°F.
  2. Melt the 5 tablespoons butter in a small light-colored saucepan over medium heat. Cook for 3 to 5 minutes, swirling, until the milk solids turn golden brown; immediately pour into a heatproof bowl.
  3. Mash the sweet potato flesh with browned butter, half-and-half, brown sugar, vanilla, salt and nutmeg. Let cool until warm rather than hot, then beat in the eggs.
  4. Grease a 2-quart baking dish with the teaspoon butter and spread in the filling. Bake for 25 to 30 minutes until the center reaches 160°F.
  5. Scatter marshmallows evenly over the hot filling and bake for 5 minutes more, watching closely, until puffed and golden. Rest for 10 minutes before serving.