Preheat the oven to 350℉ (170℃ or 160℃ for a fan oven).

Lightly butter an 8 inch square pan.

Cream together the butter, flour and white sugar. Pat the mixture into the pan.

Bake for about 10 minutes. Set aside.

Mix together the coconut, walnuts, brown sugar, baking powder and eggs in a medium bowl.

Spread the mixture over the base evenly.

Bake for about 15 minutes or until golden brown.

The squares often look very brown when they come out of the oven but don’t worry, that is exactly as it should be. Set them aside to cool.

When the squares are cool, make the frosting.

Beat together the ¼ cup softened butter and the confectioner's sugar.

Add the vanilla and beat together well.

Gradually add the lemon juice, a tablespoonful at a time, beating well after each addition until you get a smooth, spreadable frosting.

Spread the frosting over the squares in the pan. Chill in the fridge before cutting in small squares. Store covered in the refrigerator.