1Combine 1/2 cup water and 1/2 cup granulated sugar in a saucepan.
2Heat the mixture until the sugar is fully dissolved.
3Mix in 1 tablespoon of dark cocoa powder.
4Pour the simple syrup into a jar to cool.
5In a large mixing bowl, whisk together 2 cups all-purpose flour, 2 cups granulated sugar, 3/4 cup dark cocoa powder, 2 teaspoons baking powder, 1.5 teaspoons baking soda, and 1 teaspoon fine salt.
6In a separate bowl, combine 1 cup warm water, 1 cup sour cream, 1/2 cup vegetable oil, 2 large eggs, 2 teaspoons vanilla extract, and 1 teaspoon instant espresso.
7Whisk the wet ingredients together until well combined.
8Pour the wet ingredients into the dry ingredients.
9Whisk until the cake batter is smooth.
10Line and grease 8-inch cake pans with parchment paper.
11Divide the batter evenly into the prepared cake pans.
12Bake at 350 degrees Fahrenheit for 22 to 26 minutes.
13While cakes bake, prepare the chocolate frosting by mixing 2 cups unsalted butter, 1 cup dark baking cocoa, 1 teaspoon vanilla extract, and 1/2 teaspoon salt.
14Mix in 5 cups of powdered sugar and 3/4 cup of heavy cream on low speed.
15Add 1 1/3 cups of melted and cooled dark chocolate to the frosting mixture.
16Mix until smooth and well combined.
17Brush the cooled cake layers with the prepared chocolate simple syrup.
18Spread an even layer of chocolate frosting on the first cake layer.
19Place the second cake layer on top and repeat the brushing and frosting steps.
20Place the third cake layer on top and repeat the brushing and frosting steps, covering the top and sides of the cake with a thick layer of frosting.
21Decorate the cake with extra cake crumbs (optional).