Toasted Marshmallow Sweet Potato Casserole

Why You’ll Love This Recipe

• Buttery, ultra-smooth mashed sweet potatoes with warm cinnamon and vanilla.
• Classic, crowd-pleasing marshmallow topping that toasts into a caramelized cap.
• Roasting the potatoes concentrates flavor for natural sweetness—less sugar needed.
• Make-ahead friendly: assemble the base in advance and finish with marshmallows before serving.

Grocery List

• Produce: 3 1/2 lb sweet potatoes
• Dairy: Unsalted butter, whole milk or half-and-half
• Pantry: Light brown sugar, pure vanilla extract, ground cinnamon, ground nutmeg, fine sea salt, mini marshmallows, nonstick spray or butter for the dish

Full Ingredients

Mashed Sweet Potato Base

• 3 1/2 pounds sweet potatoes (about 5–6 medium)
• 6 tablespoons unsalted butter, melted
• 1/2 cup packed light brown sugar (100 g)
• 1/2 cup whole milk or half-and-half (120 ml)
• 2 teaspoons pure vanilla extract
• 1 teaspoon ground cinnamon
• 1/4 teaspoon ground nutmeg
• 3/4 teaspoon fine sea salt

Marshmallow Topping

• 1 (10-ounce) bag mini marshmallows (about 5 cups)

For the Pan

• 1 tablespoon unsalted butter (or nonstick spray) for greasing

Step-by-Step Instructions

Step 1: Roast the sweet potatoes for maximum flavor

Preheat the oven to 425°F (220°C). Line a rimmed baking sheet with foil or parchment for easy cleanup. Scrub the sweet potatoes and pat dry. Prick each potato 5–6 times with a fork and place on the prepared sheet. Roast until a knife slides through the center with no resistance, 50–60 minutes depending on size. Rotate the pan halfway for even cooking.

Step 2: Cool briefly and peel

Let the potatoes cool on the pan for 10 minutes until comfortable to handle. Peel by splitting lengthwise and scooping out the flesh with a spoon. Transfer to a large mixing bowl. Discard the skins.

Step 3: Mash to your preferred texture

Mash the sweet potato flesh until smooth with a potato masher or press through a ricer for an ultra-silky texture. Avoid using a food processor, which can make the mixture gluey.

Step 4: Stir in butter, sugar, vanilla, and spices

Pour in the melted butter, brown sugar, milk or half-and-half, vanilla, cinnamon, nutmeg, and salt. Stir until fully combined and creamy. Taste and adjust salt or cinnamon as needed—the base should be gently sweet with warm spice notes.

Step 5: Assemble and bake to set

Reduce the oven temperature to 350°F (175°C). Grease a 9×13-inch baking dish with butter or spray. Spread the sweet potato mixture evenly in the dish, smoothing the surface. Bake uncovered until the edges are gently puffed and the center is steaming, 20–25 minutes.

Step 6: Add the marshmallow cap and broil

Remove the dish and scatter the mini marshmallows in an even, edge-to-edge layer. Switch the oven to broil. Return the dish to the middle rack and broil until the marshmallows are deeply golden with caramelized spots, 30 seconds to 2 minutes. Watch constantly and rotate the pan for even browning.

Step 7: Rest and serve

Let the casserole stand for 10 minutes to set the topping. Scoop and serve warm, making sure each portion gets some of the caramelized marshmallow cap.

Pro Tips

• Roast vs. boil: Roasting concentrates flavor and keeps the mash from getting watery. If boiling, peel and cube 3 lb sweet potatoes, simmer until tender (15–20 minutes), then drain well and return to the hot pot for 1 minute to steam off moisture.
• Silky texture: Use a potato ricer or mash by hand. An electric mixer on low works too, but stop as soon as the mixture is smooth.
• Sweetness balance: A good pinch of salt brightens flavor and balances the marshmallows. You can reduce brown sugar to 1/3 cup for a less-sweet base.
• Broiler control: Keep the rack in the middle to avoid scorching. The marshmallows go from golden to burnt within seconds—do not walk away.
• Even topping: Smooth the base and cool it 3–5 minutes before topping so marshmallows toast without sinking.

Variations

• Maple-vanilla: Swap 2 tablespoons of the brown sugar for pure maple syrup and add 1 extra teaspoon vanilla.
• Orange-spice: Add 1 teaspoon orange zest and a pinch of ground ginger to the base for a citrusy lift.
• Nutty edge: Sprinkle 1/2 cup chopped toasted pecans around the perimeter before broiling to keep nuts crunchy without hiding the marshmallow top.

Storage & Make-Ahead

Refrigerate leftovers covered for up to 4 days. Reheat at 325°F (165°C) until warmed through; tent with foil if the marshmallows brown too fast. For make-ahead, prepare the mashed sweet potato base up to 2 days in advance and refrigerate in the baking dish (no marshmallows). Bake at 350°F (175°C) until hot, then add marshmallows and broil. To freeze, freeze the base (without topping) up to 2 months; thaw overnight in the fridge, reheat, then top and broil.

Nutrition (per serving)

Approximate: 420 calories; 9 g fat; 83 g carbohydrates; 4 g protein; 230 mg sodium. Values will vary based on brands and exact measurements.