Pre-heat the oven to 325°F.
Butter and lightly flour a 9-inch x 5-inch x 3-inch loaf pan, or spray it with a butter-flour spray. In a large bowl, on the medium speed of an electric mixer, cream the butter until smooth. Add the sugars and beat until fluffy, about 3 minutes. Add the egg and beat well, then the buttermilk (or substitute) and vanilla. Sift the flour, cocoa, baking soda, baking powder and salt together right into your wet ingredients. Stir together with a spoon until well-blended, but do not over mix. Scrape down the batter in the bowl, making sure the ingredients are well blended. Fold in chocolate chips – do not over mix.
Pour the batter into the prepared loaf pan. Bake for 60-70 minutes, or until a cake tester inserted into the center of the loaf comes out clean. Cool in pan on a rack for about 10-15 minutes, then turn out of pan and finish cooling on a cooling rack. Dust with powdered sugar and other toppings, if desired.