Yellow and chocolate cake batters are layered together to create a gorgeous two-layer Zebra Cake. Filled and covered with a silky smooth chocolate frosting!
Make the Cake: Preheat oven to 350 degrees F. Grease and flour two 8-inch round cake pans; set aside.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt; set aside.
Using an electric mixer, cream together butter and sugar until light and fluffy, about 3 to 5 minutes. Scrape down the sides of the bowl and beat in the eggs, one at a time, beating for 1 minute between each addition. Beat in vanilla extract.
Add the dry ingredients all at once and beat on low speed until just combined.
Add the buttermilk and beat on low for 1 minute, then increase the speed to medium and beat for 3 additional minutes.
Make the Chocolate Batter: Transfer 2 cups of the batter to a separate medium bowl. Gently whisk in the cocoa powder and milk until completely incorporated.
Drop a large spoonful (I use a medium cookie scoop for this!) of one batter in the center of each pan. Top with a spoonful of the other batter. Alternate spoonfuls on top of each other until you’ve used all of the cake batter. Give each pan a gentle shake to level out the batter.
Bake for 28 to 32 minutes, or until a skewer inserted into the center of the cake comes out with a few moist crumbs attached. Remove from the oven and cool for 10 minutes in the pans, then turn out onto wire racks and cool completely before frosting.
Make the Frosting: In a food processor, process the butter, powdered sugar, cocoa powdered, and salt until smooth, about 30 seconds, stopping once to scrape the sides of the bowl. Add the corn syrup and vanilla and process until just combined, 5 to 10 seconds. Scrape the sides of bowl, then add the melted chocolate and pulse until smooth and creamy, 10 to 15 seconds.
Assemble the Cake: Place one of the cake layers on a serving platter and spread 1 cup of the frosting evenly over the surface. Place the second cake layer on top. Use the remaining frosting to frost the top and sides of the cake. The cake can be kept at room temperature for up to 1 day before serving. Once cut, leftovers should be stored in an airtight container at room temperature for up to 4 days.