Preheat oven to 350° F. Grease two 9 inch pans with oil spray or with melted butter. Then line them with parchment paper. Grease the parchment paper as well. Set aside.
Add 2 teaspoon white vinegar into milk, mix and set aside. Instead of white vinegar, we can also use the same amount of lemon or lime juice.
Sift cake flour, baking soda, baking powder, salt, and cocoa powder together. Whisk well and set aside.
In a stand mixer using a paddle attachment or with a hand-held electric mixer, beat the butter and sugar until light and fluffy. Scrape the sides and bottom of the bowl with a spatula as needed.
Add oil, sour cream, 1 teaspoon white vinegar, and vanilla. Mix until everything is well combined and the mixture is smooth.
Then add dry ingredients and prepared buttermilk, mix on low speed until just combined. Scrape the sides and bottom of the bowl.
Add red food gel color and mix at low speed until the color is incorporated evenly into the batter. I had to use 1 tablespoon of red gel color, but you may need to use less or more depending on which color you are using. So initially add few drops of color, and then add it gradually as needed. But while adding color, make sure not to mix the batter vigorously.
Pour the batter evenly into two pans. We can weigh the batter and pour the same exact amount of batter in each pan for even distribution.
Bake the cake layers for 25 - 30 minutes or until the cake tester inserted into the center comes out clean.
Remove the pans from the oven and transfer them onto a cooling rack. Allow them to cool completely in the pan before removing.