Lemon Traybake Cake With Cream Cheese Frosting And Lemon Curd Drizzle

This is my favourite cake. The sponge is so light and fluffy, and the cream cheese frosting compliments the lemon so much.
Ingredients:
3 medium lemons
185g butter or margarine. (I use clover)
185g caster sugar
3 large eggs
190g self raising flour
1 tsp baking powder
40g butter
90g cream cheese
180g icing sugar
2 tsp lemon curd