Sweet Potato Soufflé Recipe

Preheat and prep

Preheat the oven to 350°F (175°C). Grease a 9x9-inch (or similar 8-9 inch square) ovenproof baking dish with 1 tablespoon butter and optionally dust lightly with 1 teaspoon granulated sugar; set aside.

Mash and combine

If you haven't already cooked the sweet potatoes, roast or boil until very tender, then drain and peel. Measure 3 cups of hot mashed sweet potato and place in a large mixing bowl.

Warm milk and butter

In a small saucepan over low heat, warm 1 cup milk with 4 tablespoons butter until the butter melts and the mixture is warm but not boiling. Remove from heat.

Make batter

To the bowl with mashed sweet potatoes add 4 large eggs, 1 cup granulated sugar, 1 tablespoon light brown sugar, 2 teaspoons vanilla extract, 1 teaspoon ground cinnamon, 1/4 teaspoon ground nutmeg, and 1/2 teaspoon salt. Pour in the warm milk and butter mixture and whisk until smooth. Whisk in 2 tablespoons all-purpose flour until incorporated and the batter is slightly thickened and cohesive.

Fill dish

Pour the sweet potato batter into the prepared baking dish and smooth the top with a spatula so it's even.

Make crumble dough

In a medium bowl, combine 1.25 cups all-purpose flour, 3/4 cup packed light brown sugar, 2 tablespoons granulated sugar, 1/2 teaspoon baking powder, 1/2 teaspoon ground cinnamon and 1/4 teaspoon salt. Add 4 tablespoons cold cubed unsalted butter.

Cut butter into dry ingredients

Using a pastry cutter, two knives, or your fingertips, work the cold butter into the dry ingredients until the mixture forms pea-sized crumbs and some larger crumbly pieces (a coarse crumble). Chill the crumble in the refrigerator for 10 minutes to firm up slightly if your kitchen is warm.

Top the soufflé

Evenly sprinkle the brown sugar cookie crumble over the sweet potato batter, covering the surface. Gently press some crumbs into the batter so they adhere slightly but keep much of the crumb texture on top.

Initial bake

Place the dish in the preheated 350°F (175°C) oven and bake for 30 minutes. The sweet potato base should be set around the edges but still slightly jiggly in the center.

Add marshmallows and finish baking

Remove the dish from the oven and evenly scatter 2 cups mini marshmallows over the cookie crumble topping. Return to the oven and bake for an additional 6–10 minutes, or until marshmallows are puffed and lightly golden and the center of the sweet potato base is set (a toothpick inserted near the center should come out mostly clean with a few moist crumbs).

Optional broil for color

If you want a deeper golden-brown marshmallow top, switch the oven to broil on high for 30–60 seconds and watch carefully until marshmallows achieve desired coloring. Remove immediately to avoid burning.

Rest and serve

Allow the soufflé to cool and rest for 10–15 minutes to set. The center will settle slightly while remaining light and airy. Serve warm in squares, spooning any marshmallow that has melted into the topping back over portions.