Think of us as your fairy godmother (at least when it comes to dessert) because we are making magic with this dessert. Vanilla cake topped with chocolate frosting is already pretty magical on its own, but this recipe defies everything we’ve come to know about baking. As it bakes, the cake batter transforms into three distinct layers: a rich and luxurious crust, a creamy custard center and a delicate angel food cake topping.
The magic is actually just science. Proteins make up about 10% of an egg white’s structure. When you start to whip the whites and see those frothy bubbles appear, those are the proteins starting to activate. The longer you whip the egg whites, the stronger the proteins become and the sturdier their structure will be (but make sure not to overwhip or the structure will be compromised). You’re also whipping a lot of air into the egg whites, which will be responsible for their light and delicate texture. The whipped egg whites are eventually folded into an otherwise straightforward cake batter. As the cake bakes, the egg whites expand upward and the egg yolks settle to the bottom, forming those magical layers.
Flavorwise, this cake can rumble with the rest of them. Each layer is buttery and rich, and the chocolate ganache on top makes it decadent. The ganache is made with a simple combination of chocolate chips (either dark or milk chocolate) and warmed heavy cream. Lather it on thick and top with your favorite sprinkles — we’re partial to rainbow hues.
Technique Tip: Fold egg whites into the batter gently so they will naturally inflate and form their own layer.
- 4 large eggs, separated
- 1 cup granulated sugar
- 8 tablespoons (1 stick) unsalted butter, melted
- 1 tablespoon vanilla extract or 1 teaspoon vanilla bean paste
- 1 cup all-purpose flour
- 1/4 teaspoon kosher salt
- 2 cups milk, room temperature
- 1/4 teaspoon cream of tartar
- 3 ounces (1/2 cup) semi-sweet or milk chocolate, chopped
- 1/4 cup heavy cream
- Rainbow sprinkles, for garnish
Preheat the oven to 325 degrees F and grease an 8- or 9-inch square metal or glass baking pan.2.
With an electric hand mixer, beat the egg yolks and sugar together in a large bowl on low speed for about 1 minute, until the yolks and sugar form a pale, thick paste.3.
Slowly pour in the melted butter and the vanilla extract and mix until incorporated.4.
In a small bowl, combine the flour and salt. Slowly whisk in 1/3 of the flour into the wet ingredients until blended, then whisk in 1/3 of the milk. Repeat with the flour and milk until all ingredients thoroughly combined.5.
With an electric hand mixer or stand mixer fitted with the whisk attachment, beat the egg whites for about 1 minute on medium-high speed until thick and foamy.6.
Add the cream of tartar and beat for about 1 minute more until stiff peaks form. Gently and slowly fold the egg whites into the liquid batter with a spatula.7.
Pour the batter into the greased pan and bake for about 45 minutes to 1 hour. The cake is done when it has risen high in the pan with a golden brown top crust, and barely jiggles when you gently shake the pan. Transfer to a wire rack and cool completely in the pan.8.
When the cake is cool, make the ganache: Pour the chopped chocolate into a medium bowl. Heat the cream to a simmer, then pour over the chocolate. Let the chocolate and cream rest for 1 to 2 minutes, then gently stir until the chocolate is completely melted.
Pour the ganache over the cake and gently spread with a spatula until the cake is evenly covered. Sprinkle with rainbow sprinkles or other decoration as desired. Refrigerate for at least 2 hours until the ganache has hardened.