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, baking soda, salt, and cocoa powder until well combined.
In another bowl, mix the vegetable oil, buttermilk, eggs, red food coloring, vanilla extract, and vinegar until smooth.
Gradually add the wet ingredients to the dry ingredients, mixing until just combined. Do not overmix.
Divide the batter evenly between the prepared cake pans. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes, then turn them out onto wire racks to cool completely.
While the cakes are cooling, prepare the cream cheese frosting. In a large bowl, beat the softened cream cheese and butter together until smooth and creamy.
Gradually add the powdered sugar and vanilla extract, mixing until well combined. If the frosting is too thick, add milk a tablespoon at a time until desired consistency is reached.
Once the cakes are completely cool, place one layer on a serving plate and spread a layer of cream cheese frosting on top. Place the second cake layer on top and frost the top and sides of the cake with the remaining frosting.
Serve immediately or refrigerate for up to 3 days.