
Here's the recipe, from the Fannie Farmer Cookbook.
Chocolate Buttermilk Cake
1 2/3 cups flour
1 cup sugar
1/2 cup cocoa
1 teaspoon baking soda
1/2 teaspoon salt
1 cup buttermilk
1/2 cup vegetable oil
2 teaspoons vanilla
Preheat oven to 350. Butter and lightly flour 2 8-inch round cake pans or one 9 x 13 inch pan. Mix the flour, sugar, cocoa, baking soda, and salt in a bowl. Add the buttermilk, vegetable oil, and vanilla, bewating until smooth. Spread in the pans and bake about 20-25 minutes. Cool for 5 minutes before turning out on rack.
My tips: Use really good cocoa and good vanilla. That imitation vanilla will ruin anything it touches.