First sift the flour with the cornflour (cornstarch), baking powder and baking soda, and set it aside. Make the espresso, add piping hot milk, mix and pour it over the cocoa powder, stir well to dissolve the cocoa and set it aside to cool down. Beat the softened butter with the sugar, on high, until light and fluffy, then beat in the eggs, one at a time, beating well after each, then beat in the vanilla.