Preheat oven to 350° F, butter and flour a 8-inch cake pan (or springform pan) and line bottom with parchment paper. With electric beaters, cream butter and sugar together. Cut marzipan into chunks and beat into butter mixture (if marzipan is firm, soften in microwave for 30 seconds on high) until smooth. Add eggs one at a time, mixing well after each addition and stir in lemon zest and extracts. In a separate bowl, sift together flour, baking powder and salt. Add to marzipan mixture and blend until smooth. Pour into prepared pan and bake for 35 to 45 minutes, until a tester inserted in the centre of the cake comes out clean. Allow to cool in pan for 20 minutes, then turn out onto a plate to cool completely. Dust with icing sugar.
Marzipan cake will keep up to 5 days in an airtight container.
Yield: 1 8-inch cake. Makes 8 to 10 servings.