Preheat oven to 350°F (175°C).

Cream the butter, shortening, and sugar together in a large bowl until light and fluffy.

Add eggs, one at a time, beating well after each addition.

Sift together flour, cocoa, soda, and salt in a separate bowl.

Gradually add the dry ingredients to the creamed mixture alternately with the buttermilk, beginning and ending with the dry ingredients.

Stir in coffee and vanilla extract.

Pour batter evenly into two greased and floured 9-inch cake pans.

Bake for 35 minutes, or until a toothpick inserted into the center comes out clean.

Let cool in pans for a few minutes before inverting onto a wire rack to cool completely.

Frost with your favorite German chocolate frosting (not included in these instructions).