Chocolate Birthday Sheet Cake With Strawberry Marshmallow Frosting

• For the cake
• 2 cups cake flour, sifted
• 3/4 cup Dutch Process Cocoa Powder
• 1 cup packed light brown sugar
• 1 cup granulated sugar
• 1 3/4 teaspoons baking powder
• 1 teaspoon baking soda
• 1 teaspoon table salt
• 1 egg, room temperature
• 2 egg yolks, room temperature, save the whites for the frosting
• 1 tablespoon pure vanilla extract
• 1/2 cup vegetable oil
• 1 cup sour cream, room temperature
• 1 cup boiling water
• 1 tablespoon espresso powder
• For the frosting
• 1 cup sliced strawberries, plus more for decorating
• 2 egg whites
• 1/2 cup plus 2 tablespoons, granulated sugar
• 1/4 teaspoon cream of tartar
• 1/4 cup light corn syrup
• 1/8 teaspoon table salt
• 1 1/2 teaspoons lemon juice, or more to taste

1. Preheat the oven to 350u0b0F. Grease a 13-by-9-by-2-in pan with nonstick cooking spray or softened butter and line with parchment paper.
2. Add the flour, cocoa powder, brown sugar, granulated sugar, baking powder, baking soda, and salt to the bowl of a stand mixer fitted with the paddle attachment; mix on low speed until well combined.
3. In a small bowl, or in a large 4-cup liquid measuring cup (my preference), add the egg, egg yolks, vanilla, oil, and sour cream and whisk until combined. With the mixer on medium-low speed, slowly pour the wet ingredients into the dry ingredients. Beat until incorporated, scraping down the bowl with a rubber spatula as needed.
4. In the same small bowl/measuring cup, no need to clean it, combine the boiling water and espresso powder and add to the batter in the mixer bowl. Mix again on medium speed for 30 seconds, until smooth, scraping the bowl with a rubber spatula as needed. The batter will be quite thin
5. Pour the batter into the prepared pan and bake for 28 to 32 minutes, rotating at the halfway point. The cake is ready when a toothpick inserted in the middle comes out with a moist crumb or two. Let cool completely in the pan. Or let cool enough so you can comfortably handle it, and invert the cake on to a serving plate to continue cooling. If you would rather serve slices directly from the pan, let cool to room temp before frosting.
6. In a food processor fitted with the metal blade, or in a blender, process the berries until pureed. Place a sieve over a small bowl, pour the puree into the sieve, and using a rubber spatula, press the puree through the sieve to remove the seeds. Set aside.
7. Add the egg whites, sugar, corn syrup, cream of tartar, and salt in the now-cleaned bowl of the stand mixer and nestle it in a saucepan of simmering water over medium-high heat. Donot allow the bottom of the bowl to touch the water. Whisk until the mixture is just warm to the touch. Remove the bowl from the heat, add the puree and transfer it to the stand mixer fitted with the whisk attachment. Mix on high speed until stiff and glossy, about 7 minutes. Add the lemon juice and whisk a final time to combine.
8. Once the cake is cool, generously frost it and sprinkle the top with pink sanding sugar. The frosted cake is best served within a few hours with a few sliced strawberries on each plate - or, a scoop of strawberry ice cream - I mean this is a birthday cake, after all.

cake, cake flour, dutch, brown sugar, sugar, baking powder, baking soda, salt, egg, egg yolks, vanilla, vegetable oil, sour cream, boiling water, espresso powder, frosting, strawberries, egg whites, sugar, cream of tartar, light corn syrup, salt, lemon juice

Taken from food52.com/recipes/80430-chocolate-birthday-sheet-cake-with-strawberry-marshmallow-frosting (may not work)