Combine 1 cup sugar, cocoa, water and 1 teaspoon vanilla in a saucepan. Heat over medium-low heat to the boiling point, but do not boil. Set aside.
In a large bowl, cream together 1 1/2 cup sugar and butter. Beat in eggs. Stir in milk and 1 teaspoon vanilla. Combine flour and baking powder; mix into the creamed mixture. Divide batter into the pastry shells. Pour 1/3 of the cocoa mixture on top of the cake batter in each pastry shell.
Bake at 180 degrees C for 25 to 35 minutes, or till set.