Preheat oven to 350°F (180°C)
1. In a bowl, sift cake flour and salt together two times. Set aside.
2. In a mixer bowl fitted with paddle attachment, cream butter and sugar until light and fluffy, for 3 minutes. Add eggs, one at a time, beating well between each addition.
3. In a small bowl, combine cocoa powder, food coloring and vanilla. Beat into butter mixture. Using a wooden spoon, stir in flour mixture alternating with buttermilk, making three additions of flour and two of buttermilk just until blended.
4. In another small bowl, combine vinegar and baking soda. As soon as mixture starts to bubble, fold into batter by hand.
5. Divide batter evenly between prepared pans. Bake in preheated oven until a toothpick inserted into center comes out clean, 22 to 26 minutes. Let cool in pans on a wire rack for 10 minutes before transferring to rack to cool completely.
6. For best results for decorating, wrap cakes in plastic wrap and freeze for 1 to 2 days. Decorate with any of the icings(see Notes) or one of your favorites.