1. Preheat oven 350˚F. Lightly grease and flour a 9×5 inch loaf pan.
2. In a stand mixer, cream together butter, sugar, vanilla, espresso powder, and cocoa powder.
3. Add eggs one at a time, beating well after each addition. Scrape down the sides of the bowl midway through the mixing process.
4. Add half the Pioneer Buttermilk Baking Mix to the bowl, followed by all the milk, mixing at a low speed.
5. Add the remaining Pioneer Buttermilk Baking Mix, beating until the batter is smooth.
6. Pour the batter into the prepared pan, and bake for 60 minutes, or until a thin knife inserted into the center comes out clean.
7. Remove the cake from the oven; cool for 10 minutes before turning the cake out onto a cooling rack.