That's not icing you see on the top of this cake. It's a pudding that forms on the bottom as the cake bakes, and dresses the top of the cake after it's inverted. I adapted it from a recipe by Maida Heatter, "America's First Lady of Desserts", who describes it thusly:
"When it is turned onto a cake plate, it covers itself with a thick layer of dark chocolate topping that resembles nothing I can think of. The topping is as dark and shiny as black patent leather, as tender and semifirm as a pot de crème, and as mocha-chocolate flavored as you might weave dreams about."It's remarkably easy to make. And for all it's creamy dark chocolate decadence, it (don't tell the FRE) has about half the fat of a comparably sized brownie. Honest-to-god, you have to give this one a go.
Ingredients - Cake
1 cup all-purpose flour
1 1/2 tsp. baking powder
1/2 tsp. baking soda
1/4 tsp. salt
2 tbsp. unsweetened cocoa powder
1/2 cup sugar
1/2 cup non-fat milk
1/4 cup non-fat buttermilk (or plain yogurt)
1 tsp. vanilla extract
1 tbsp. melted butter
1 tbsp. vegetable oil (I used unrefined peanut)
1/2 cup chopped walnuts
Ingredients - Topping
2/3 cup granulated sugar
2 tbsp. mild molasses (not blackstrap)
1 tbsp. maple syrup
6 tbsp. unsweetened cocoa powder
2 tsp. instant coffee (substitute half of this with instant espresso powder if you have it)
1/8 tsp. salt
1 cup water
dash vanilla extract
1 Preheat the oven to 350°F. Rub a thin layer of vegetable oil on the insides of an 8 inch cake pan.
2 Combine all the topping ingredients in a small saucepan and heat at the very lowest setting as you prepare the cake.
3 Sift together the first 6 cake ingredients (flour, baking powder/soda, salt, cocoa, sugar). Melt butter (20 seconds in a microwave should do it). In a separate bowl, whisk together the milk, buttermilk, vanilla, melted butter, and oil.
4 Combine the wet and dry cake ingredients. Stir until completely blended. Stir in the walnuts. Pour into the oiled cake pan.
5 Turn up the heat on the saucepan and bring the sauce to a rolling boil. Carefully ladle the hot liquid over the unbaked cake batter. (The two will trade places as the cake bakes, leaving the topping on the bottom and the cake on top.)
To the right you see the boiled sauce floating on top of the uncooked cake batter.
6 Bake for 40 to 45 minutes or until a toothpick inserted into the middle, no more than 1/4 inch deep, comes out clean.
7 Allow the cake to cool, about an hour. Cover the top of the cake with a flat plate or cutting board, turn over, and tap the bottom of the pan gently (or more vigorously if your cake is stubborn), until the cake dislodges. Some of the topping will stick to the bottom of the pan. Just scoop this up and spread over the cake. Resist licking. Or not.