Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt until well combined.

In another bowl, combine the Dr Pepper, vegetable oil, eggs, and vanilla extract. Mix until well blended.

Gradually add the wet ingredients to the dry ingredients, stirring until just combined. Be careful not to overmix.

Divide the batter evenly between the prepared cake pans.

Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Once baked, allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

In a mixing bowl, beat the softened butter until creamy.

Gradually add the powdered sugar and cocoa powder, mixing until combined.

Add the vanilla extract and Dr Pepper. Beat until the frosting is fluffy and smooth.

Once the cakes are completely cool, place one layer on a serving plate.

Spread a layer of frosting on top of the first cake layer.

Place the second cake layer on top and use the remaining frosting to cover the top and sides of the cake.

Optional: Decorate with chocolate shavings or sprinkles if desired.

Slice and serve the cake to enjoy!