01 - Preheat oven to 350°F. Grease and flour two 9-inch round cake pans.
02 - In a medium bowl, sift together flour, sugar, baking soda, salt, and cocoa powder until well blended.
03 - In a large bowl, whisk together oil, buttermilk, eggs, food coloring, vanilla, and vinegar until fully incorporated.
04 - Gradually add the dry ingredients to the wet ingredients, mixing gently until smooth and no lumps remain.
05 - Divide the batter evenly between the prepared cake pans, smoothing the tops with a spatula.
06 - Bake for 28-30 minutes, or until a toothpick inserted into the center comes out clean.
07 - Let cakes cool in pans for 10 minutes, then carefully transfer to a wire rack to cool completely.
08 - Beat cream cheese and butter until smooth and creamy. Add powdered sugar gradually, then vanilla and salt. Beat until light and fluffy.
09 - Place one cake layer on a serving plate. Spread an even layer of frosting on top. Position the second layer over the first and frost the top and sides completely.
10 - Refrigerate the cake for 30 minutes before slicing to ensure clean, neat cuts.