~ for the cake:
1 1/2 c flower
1/3 c cocoa powder
1 tsp baking soda
1/2 tsp salt
1 c sugar
1/2 c vegetable oil
1 c coffee
2 tsp vanilla
2 tbsp vinegar
~ for the glaze:
1/2 lb bittersweet chocolate
3/4 c 2% low-fat milk
1/2 tsp vanilla
Preheat oven to 375 degrees F.
Sift the flour, cocoa, baking soda, salt, and sugar into an ungreased 8-inch square or 9-inch round baking tin. In a 2-cup measuring cup, measure and mix the oil, water or coffee, and vanilla. Pour the liquid ingredients into the baking tin and mix the batter with a fork or small whisk. When the batter is smooth, add the vinegar and stir quickly. Pale swirls will occur where the vinegar and baking soda react. Stir just until the vinegar is evenly distributed throughout the batter. Bake for 25-30 minutes. Set aside the cake to cool. If you are making the glaze, reset the oven to 300 degrees F. Melt the chocolate in a small ovenproof bowl or heavy skillet in the oven for about 15 minutes. Stir the hot liquid and vanilla into the chocolate until smooth.
Spoon the glaze over the cooled cake. Refrigerate the glazed cake for a minimum of 30 minutes before serving.