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

In a large mixing bowl, sift together the flour, cocoa powder, baking powder, baking soda, and salt.

In another bowl, whisk together the vegetable oil, granulated sugar, and eggs until well combined. Add the buttermilk, blue food coloring, and vanilla extract. Mix until the batter turns a vibrant, even blue.

Gradually add the dry ingredients into the wet mixture, mixing on low until fully incorporated. Be careful not to overmix.

Divide the batter evenly between the two prepared pans. Smooth the tops with a spatula.

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

Let the cakes cool in the pans for 10 minutes, then transfer to wire racks to cool completely.

While your cakes are cooling, beat the cream cheese and butter together in a mixing bowl until smooth.

Gradually add the powdered sugar and vanilla extract, mixing until creamy and fluffy.

Once the cakes are completely cool, spread a generous amount of cream cheese frosting between the layers and cover the top and sides of the cake with the remaining frosting.

Decorate as desired.