Ingredients

Cake:
1 cup sifted all-purpose flour
1 tsp baking powder
1/2 tsp baking soda
1/8 tsp salt
1/4 pound unsalted butter
1 tsp vanilla extract
1 cup sugar
1 egg
1/2 cup powdered, unsweetened cocoa
1/2 cup milk
1 tbsp instant coffee
1/2 cup boiling water

Icing:
4 ounces quality, semi-sweet chocolate
2 ounces butter, cut in 4 pieces

Method

1. Adjust rack to 1/3 up from the bottom of the oven and preheat to 350 degrees.
2. Butter a 9-inch sqaure cake pan and dust the bottom only, very lightly with dry bread crumbs
3. Sift together the flour, baking soda, baking powder, and salt. Set aside.
4. In a small bowl of electric mixer cream the butter. Add the vanilla and sugar and beat for a minute or so.
5. Beat in the egg.
6. On lowest speed add the cocoa.
7. Then, in this order, gradually add one-half of the milk, one-half of the dry ingredients, and the remaining milk and then the remaining dry ingredients. Scrape the bowl often with a rubber spatula. Mix only until smooth after each addition.
8. Dissolve the instant coffee in the boiling water. While it is still hot add the this on lowest speed to the batter gradually.
9. Pour this thin batter into the prepared pan and bake for 40 minutes – or until top springs back when touched.
10. Cool on a rack in pan for about 10 minutes. Then invert onto a rack and invert to be upright on a rack to finish cooling.

Icing:

1. In the top of a small couble-boiler over hot water melt the chocolate.
2. Remove the top of the double boiler.
3. with a small wire whisk beat in the butter, 1 piece at a time, until thoroughly incorporated. Repeat to use all of the butter.
4. This icing must be used immediately.
5. To make a bit thicker, place the pan in a bowl of ice water and stir constantly until you reach your desired consistency. Don’t let this harden – it should be fluid to use.
6. Pour over the cake. when cool cut into squares.