Chef notes

There are very few things that I miss about summer, but s’mores tops the list. Truthfully, it’s not the graham crackers or melting chocolate squares that I love – it’s the toasted marshmallows.I have always enjoyed the texture and flavor of the charred outside as it mingles with the smooth, gooey inside. I decided to give my beloved s’mores an autumnal twist with this pumpkin sheet cake. Fall’s most popular flavor meets toasted marshmallows in this crowd-friendly dessert. When you toast the marshmallows, you’ll be transported back to your childhood and feel like you’re assembling s’mores by the campfire.

The pumpkin cake is super simple — all you need are two bowls and a whisk. The cake is oil-based, so it stays very moist. It is flavored with pumpkin pie spice, which is a mixture of autumn’s best warming spices such as cinnamon, ginger, nutmeg, allspice and cloves. I like to bake it in a rectangular baking sheet, but you can also use a half sheet pan if you’d rather–just reduce the baking time by about 15 minutes. A quick marshmallow frosting is piled on top of the cake before serving. All it needs is a quick turn under the broiler (or a few waves of a hand-held blow torch) to take this simple cake up a notch.

Technique Tip: If you forgot to bring your eggs to room temperature, place them in a bowl and cover them with room temperature water. In about 15 minutes, they will be ready to bake with.

Swap Option: You can use marshmallow fluff here as a frosting shortcut. Just spread about 1½ cups over the top and torch. 10 ounces of mini marshmallows work just as well!

Ingredients

For the Cake

nonstick baking spray
2 cups all-purpose flour
2 cups granulated sugar
1 tablespoon pumpkin pie spice
2 teaspoons baking soda

1 teaspoon kosher salt
1 cup vegetable oil
1 (15-ounce) can pumpkin purée
4 large eggs, room temperature

For the Frosting

3 large egg whites
3/4 cup granulated sugar

1/8 teaspoon cream of tartar
1/2 teaspoon pure vanilla extract

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Preparation

Make the cake: Preheat the oven to 350 F. Coat a 9-by-13-inch baking pan with pan spray.

In a medium bowl, whisk together the flour, sugar, pumpkin pie spice, baking soda and salt. In a large bowl, whisk together oil, pumpkin and eggs until combined. Add dry ingredients and mix until well combined and mostly smooth. Pour batter into the prepared pan, spreading to the edges with a small offset spatula. Bake until the cake pulls away from the sides of the pan and a toothpick inserted into the center comes out clean, 40 to 45 minutes. Let cool completely, about 30 minutes.

Make the frosting: Place egg whites, sugar and cream of tartar in the bowl of a stand mixer and place the bowl over a small pot of simmering water. Cook over medium heat, whisking frequently, until the mixture is smooth and warm to the touch, 2 to 3 minutes. Transfer the bowl to a stand mixer and beat with the whisk attachment on high speed until stiff, glossy peaks form, 6 to 8 minutes.

Switch the oven to the broiler setting with a rack 6-inches below the heating element. Spread the frosting evenly over the top of the cake. Broil until lightly toasted, 5 to 15 seconds. Alternatively, carefully wave a blow torch over the fluff to toast.