Preheat oven to 350.
Cream shortening, sugar, salt, eggs, vanilla and butter flavoring.
Make a paste of cocoa and red food color. Add to first mixture. Alternately add flour and buttermilk. Mix vinegar and soda in a small bowl. Add to batter, blend.
Bake in 3 9 inch pans for 20-25 minutes at 350, or until cake tests done. Let cool completely. Cover with frosting
Cook flour, salt, and milk until thick, stirring constantly. Let cool. Cream shortening and sugar very well. Add vanilla dn butter flavoring, combine with first mixture; blend well.