Chocolate Cake

1 cup sugar
1 Tbsp. butter
1 egg yolk
pinch of salt
2 squares melted chocolate in 1 cup boiling water
1 1/2 cups flour
1 tsp. baking powder

Cream sugar, butter and egg, then add other ingredients. Beat well and add another 1/2 cup warm water with 1/2 tsp. soda dissolved in it. Then add 1 tsp. vanilla. Bake in a moderate oven.