• Preheat oven to 350°F. Line two 9-inch cake pans with parchment paper circles and spray sides with baking spray.

Chocolate Cake

• Whisk flour, sugar, cocoa powder, baking soda, baking powder, and salt together in a large bowl.
• Add the buttermilk, oil, eggs, and vanilla and mix on medium speed using a hand mixer or stand mixer until combined.
• Add the hot water and mix on low speed until combined. Scrape bottom and sides of the bowl and mix on medium speed for 30 seconds.
• Pour into the baking dish or divide evenly between cake pans. Bake for 30-35 minutes until a toothpick inserted into the center of the cake comes out clean. Cool in the pans for 10 minutes, then turn the cake layers out onto wire racks to cool completely.

Vanilla Cake

• Wash and dry the cake pans, then line them with parchment paper circles and spray sides with baking spray again for the next batch of cake batter.
• In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
• In bowl of a stand mixer, cream sugar, butter, and oil together until light and fluffy, about 2-3 minutes, scraping down the sides of the bowl a couple of times during mixing.
• Add egg whites one at a time, beating well after each addition. Add vanilla extract. Stop and scrape the bottom and sides of the bowl.
• Add the flour mixture alternately with the milk and sour cream, about ½ of each at a time, mixing between additions just until combined.
• Divide the batter evenly between the two prepared pans. Bake for 24-28 minutes, until a toothpick inserted into the center of each cake comes out clean.
• Remove the cakes from the oven and cool for 10 minutes before running a sharp knife around the edges, then gently turning the cakes out onto a wire cooling rack to cool completely.

Frosting

• In a large bowl, beat butter and cocoa powder together until creamy and smooth.
• Gradually add powdered sugar 1 cup at a time, adding heavy cream or milk as needed and mixing well between each addition until you have a creamy, spreadable frosting. Stop and scrape down the bottom and sides of the bowl as needed.
• Add vanilla and salt. Mix well, adjusting the consistency by adding powdered sugar or milk as needed.

Assembly

• Use a long serrated knife or cake leveling tool to level the cake layers so that they are flat on top and the same height, which makes for the most clean look for a checkerboard cake.
• Cut out large 6-inch circles from the center of each cake layer using a 6-inch round cutter. Then use a 3-inch cookie cutter to cut out smaller 3-inch circles from the center of each cake layer. Eyeball carefully so the circles are cut in the very center of each cake layer for the most precise results.
• Replace the middle ring of each cake flavor with the other flavor to create a bullseye pattern that alternates with the vanilla layer or chocolate layer on the outside. The larger outer rings are the most difficult to lift and prone to breaking, so work carefully and assemble the layers on a sturdy plate that can be used to lift and flip the cake layers onto your cake plate later.
• Generously frost the bottom cake layer with the prepared frosting. The frosting helps act as a glue holding the layers of cake together. Carefully place the next cake layer on top of the first layer, alternating the color of the outer ring to build the checkerboard effect. Continue adding frosting between each layer and alternating the colors to build the cake.
• Once all four cake layers are in place, spread a thin layer of frosting around the top and sides of the entire cake for a crumb coat. This helps seal in any crumbs for a better look later when adding the final layer of frosting. Transfer the cake to the freezer for 20 minutes to set the crumb coat.
• Once the crumb coat has had a chance to firm up, frost the top and sides of the cake with the remaining chocolate frosting.
• Slice and enjoy!