Blue Velvet Cake Recipe
from Add a Pinch

1 tablespoon vinegar

1 cup buttermilk

1 teaspoon soda

1 teaspoon vanilla

1 scant teaspoon salt

2 ¼ cups all-purpose flour

2 tablespoons cocoa

2 drops violet gel paste food color

1 ounce royal blue gel paste food color

2 eggs

1 ½ cups sugar

½ cup Crisco