Set the oven to 150°C (300°F).

Grease and line a 24 cm (9½ inch) round cake tin. Cream the butter and sugar in an electric mixer for 2 minutes, or until lump free (the mixture does not need to be light and fluffy). Slowly beat in the eggs, then fold in the ground almonds, coconut, polenta, lemon zest, lemon juice, baking powder and vanilla. Pour into the cake tin and use the back of a spoon to spread the mixture and flatten the top. Bake for 30–50 minutes, or until the cake is golden and just coming away from the side of the tin. Cool in the tin then turn out onto a serving plate.

For the icing, mix the sugar and lemon juice in a bowl until smooth. Spoon over the cake, letting the icing dribble down the sides a little.

Leave the icing to set.

Variation: you can make this cake as 24 small cakes using mini muffin trays or silicon flexipans.

Bake for 20–30 minutes, or until golden.