Mix flour and making powder and sift together into a bowl. Grate the marzipan and mix with the icing sugar, soft butter and vanilla until light and fluffy. Then add the room temperature 5 eggs, 1 by one beating well after every addition. Add the salt and beat everything until creamy for at least 4 minutes with the hand mixer. Stir vanilla and add in the almond essence, if using. Then bit by bit stir in the flour-baking powder mixture, adding some of the milk in between additions of flour. Do not overmix ( see tips)