Simply Perfect Chocolate Cake

INGREDIENTS

For the chocolate cake layers

• 1 1/2 cups granulated sugar
• 1 cup all-purpose flour
• 1/2 cup cake flour
• 1 cup unsweetened cocoa powder
• 1 1/2 teaspoons baking powder
• 1 teaspoon baking soda
• 1/2 teaspoon kosher salt
• 1 cup (2 sticks) unsalted butter, softened
• 4 large eggs
• 1 cup plain Greek yogurt or sour cream
• 2 teaspoons vanilla extract

For the cocoa simple syrup (optional)

• 1/2 cup granulated sugar
• 1 tablespoon unsweetened cocoa powder
• 1/2 cup water

For the chocolate Swiss meringue buttercream

• 6 large egg whites
• 2 cups granulated sugar
• 2 cups unsalted butter, softened but still cool
• 10 ounces semi-sweet chocolate, melted and cooled slightly
• 2 1/2 tablespoons water
• 2 tablespoons unsweetened cocoa powder
• 1 teaspoon vanilla extract
• 1/4 teaspoon kosher salt

INSTRUCTIONS

To make the chocolate cake layers:

1. Preheat the oven to 325 degrees F.
2. Generously mist three 8-inch diameter by 3-inch high cake pans with non-stick spray, and line with circles cut from parchment paper.
3. Place the sugar, flours, cocoa, baking powder, baking soda, and salt in a large mixing bowl, and whisk to combine.
4. Cut the butter into smaller pieces and add it to the dry ingredients.
5. Mix on low speed until the mixture resembles damp sand (30 seconds to a minute).
6. Add the eggs, one at a time, scraping the bottom and sides of the bowl with a silicone spatula after each addition.
7. When all of the eggs are fully incorporated, add the Greek yogurt or sour cream and vanilla, and beat on medium speed for about 60 to 90 seconds, to aerate the batter and strengthen the cake's structure.
8. Divide the batter evenly between the three prepared pans, and bake for 30-40 minutes, or until a toothpick inserted in the thickest part of the cake comes out clean or with one or two moist crumbs.
9. Cool completely, then soak with cocoa simple syrup (optional)  and fill and frost with chocolate Swiss meringue buttercream.

To make the cocoa simple syrup (optional):

1. Place the sugar and cocoa powder in a small pot and whisk to combine.
2. Stir in the water and place over medium heat.
3. Cook, stirring occasionally,  until all the sugar has dissolved.
4. Place one cake layer on a serving platter.  Use a pastry brush to soak the cake with the simple syrup before topping with chocolate Swiss meringue buttercream.  Repeat as you add each layer.

To make the chocolate Swiss meringue buttercream:

1. Place the egg whites and sugar in a large mixing bowl set over a pot of simmering water.
2. Cook, whisking occasionally, until the mixture is smooth, thin, and translucent, and it no longer feels gritty when rubbed between the thumb and forefinger.
3. Remove the bowl from the heat and whisk on medium-high speed until fluffy and stiff, and no hint of warmth remains when you place your hand on the side of the bowl.
4. Add the butter, a tablespoon at a time, whipping after each addition.  If the mixture looks curdled, whip on high speed until it becomes smooth, then continue adding the butter one tablespoon at a time.  If the mixture seems runny, place it in the refrigerator for 10 to 20 minutes, then re-whip.  
5. When all the butter has been added and the mixture is fluffy and spreadable, stir in the melted chocolate.
6. Stir the water, cocoa, vanilla, and salt together in a small bowl, then add to the buttercream, stirring until completely incorporated.

by Allie {Baking A Moment}