Whisk 300g softened butter into 350g caster sugar until light in color. Next mix in 3 eggs, one at a time, until well combined. Now, by hand, add the zest of a lemon and an orange, along with 200g self-raising flour, 50g fine polenta, 50g ground almonds and 1 tsp baking powder, until well combined. Finally, add 400g of fresh fruit (or save 50g of it to put on the top), and 100g of small chopped cubes of golden marzipan, and stir carefully to mix without breaking up all the fruit.
Put in a greased (or lined) 20cm x 30cm baking tray and cook in a 180c oven for 45 mins.