Red Velvet Cake

1 Cup butter
1 1/2 cups sugar
3 eggs
1 tsp vanilla
2 1/2 cups cake flour
2 tbsp cocoa
1 1/2 tsp baking soda
1 cup buttermilk
1 1/2 tsp vinegar
2 tsp red food coloring

Beat butter and sugar until light and fluffy. Add eggs, one at a time and beat well after each egg. Add vanilla and beat. Sift dry ingredients together. Mix the buttermilk, vinegar, and coloring and add to butter mixture alternately with dry ingredients beginning and ending with flour. Bake in a greased 9 x 13 pan at 350 degrees for 30 to 35 minutes.