01 - Preheat oven to 350°F. Grease two 9-inch round cake pans and line with parchment paper.
02 - Sift flour, sugar, baking soda, salt, and cocoa powder into a large mixing bowl.
03 - Whisk together oil, buttermilk, eggs, food coloring, vanilla, and vinegar until smooth.
04 - Gradually pour wet ingredients into dry ingredients, mixing until just combined. Avoid overmixing.
05 - Divide batter evenly between pans. Bake 28-32 minutes until toothpick inserted in center comes out clean.
06 - Let cakes cool in pans for 10 minutes. Turn out onto wire racks to cool completely.
07 - Beat cream cheese and butter until creamy. Add vanilla and salt. Gradually beat in powdered sugar until fluffy.
08 - Level cake layers if needed. Place one layer on plate, spread with frosting. Top with second layer and frost top and sides.
09 - Refrigerate cake for at least 30 minutes before slicing for cleaner layers.