1. Preheat the oven to 350 degrees F (175 degrees C). Butter and dust with flour a 10 inch bundt tin. 2. Cream the butter or margarine till light and fluffy. Beat in the condensed milk. Combine the flour, cocoa powder, baking powder, and baking soda; mix into the creamed mixture alternately with the cola. 3. Bake for 45 minutes, or until the cake tests done.