White Chocolate and Raspberry Sheet Cake

For the Crème Fraîche Cake

Center a rack in the oven and preheat to 350 (F). Prepare a 9 x 13-inch rectangular baking pan by spraying generously with cooking spray and lining the bottom and sides with parchment paper. Spray the parchment paper with cooking spray and set aside.
In a medium bowl or a large liquid measuring cup, combine 3/4 cup crème fraîche, 1/2 cup whole milk, 5 large egg whites, and 2 teaspoons pure vanilla extract. Whisk to combine and set aside.
In the bowl of a freestanding electric mixer fitted with a paddle attachment, combine 2 1/4 cups all-purpose flour, 1 1/2 cup granulated sugar, 1 tablespoon plus 1 teaspoon baking powder, and 1 teaspoon kosher salt. Paddle on low speed until combined. With the mixer running on its slowest setting, add 3/4 cup cubed unsalted butter 1 to 2 cubes at a time, beating until the mixture resembles coarse, wet sand. With the mixer still running on low, slowly add half the wet ingredients (from the 2nd step). Increase the mixer speed to medium and beat for 20 seconds. Reduce the mixer speed back to its slowest setting and add the rest of the wet ingredients, before turning up the speed back to medium and beating for another 20 seconds. Be careful not to overmix! 20 seconds should be enough. After 20 seconds, turn off the mixer and use a rubber spatula to scrape down the sides of the bottom of the bowl, using the spatula to mix the batter a few more times.
Pour the batter into the prepared baking pan and transfer to the oven to bake for 35 to 40 minutes, or until a cake skewer inserted into the center of the cake comes out clean and the top of the cake bounces back when gently poked. Transfer to a wire rack and let cool completely before frosting.

For the White Chocolate Frosting and Assembly

Transfer 4 ounces white chocolate to a double-boiler (or make a homemade double-boiler by placing a heatproof glass bowl on top of a saucepan with 1 to 2 inches of water, making sure that the bottom of the bowl does not touch the water) over medium-low heat. Cook until melted, stirring constantly to prevent the chocolate from scorching. Set aside on a wire rack to cool slightly.
In the bowl of a freestanding electric mixer fitted with a paddle attachment, combine 3/4 cup unsalted butter, 1 1/2 teaspoons pure vanilla extract, 1 tablespoon light corn syrup and a pinch of kosher salt. Beat on medium speed until combined, stopping to scrape down the bottom and sides of the bowl with a rubber spatula. Turn the mixer speed back on to its slowest setting and add 1 cup confectioner's sugar, 1/4 cup at a time, continuing to beat until fully incorporated. Add the white chocolate and beat on low until combined.
Use a spoon to scoop the frosting on top of the crème fraîche cake, using an offset spatula to make rustic swirls. If the frosting is too runny, remember the baker's notes and feel free to refrigerate for 20 minutes or so to let it stiffen up again so that it's easier to work with. Top the frosting by sprinkling 2 cups fresh raspberries on top of the white chocolate frosting. Enjoy!

Get the Recipe: White Chocolate and Raspberry Sheet Cake

Ingredients

For the Crème Fraîche Cake

For the White Chocolate and Raspberry Frosting

Instructions

For the Crème Fraîche Cake

For the White Chocolate Frosting and Assembly

Notes