Preheat your oven to 350°F (175°C). Grease and flour two 8-inch square baking pans. Alternatively, you can use one 9x13 inch pan and cut it into squares later.
In a large bowl, whisk together the flour, sugar, baking soda, and salt.
In a separate medium bowl, combine the buttermilk, vegetable oil, eggs, and vanilla extract. Beat until well combined.
Pour the wet ingredients into the dry ingredients and mix on low speed until just combined. Do not overmix.
Carefully add the hot water to the batter and mix on low speed until smooth. The batter will be thin.
Divide the batter evenly between the prepared pans. Bake for 30-35 minutes for square pans, or 35-40 minutes for a 9x13 inch pan, or until a toothpick inserted into the center comes out clean.
Let the cakes cool in the pans for 10 minutes before inverting them onto a wire rack to cool completely.
While the cakes cool, prepare the frosting. In a large bowl, beat the softened butter until creamy. Gradually add the powdered sugar, alternating with the milk, and beat until smooth and fluffy. Stir in the vanilla extract.
Divide the frosting into three portions. Leave one portion white for the cream layer. Tint one portion red and the other black using food coloring.
Once the cake layers are completely cool, place one layer on your serving plate or cake board. Spread a generous layer of white frosting evenly over the top.
Carefully place the second cake layer on top of the white frosting. If using a 9x13 inch cake, you'll need to cut it into squares and assemble them on the serving plate, adding the white frosting between the 'blocks'.
Frost the top and sides of the assembled cake with the red frosting, trying to create a smooth, even surface. For a more rustic look, you can leave some texture.
Using the black frosting, pipe or spread it onto the cake to create the iconic 'cracks' and edges of the Minecraft cake. You can use a piping bag with a small round tip or a ziplock bag with a corner snipped off.
Optional: Sprinkle a few chocolate sprinkles around the base of the cake to mimic the 'dirt' or 'grass' blocks.