Every time I bake lemon bars (regardless of recipe), I seem to end up with a foamy cake-like layer on top of the lemon curd. I'm not really sure where I am going wrong, but it is definitely a technique over recipe thing because regardless of the recipe I have this problem.
EDIT: I make my own lemon curd, I don't buy it. Despite me varying recipes, and trying to vary my technique I still end up with a foamy cakey layer on top. The lemon mixture on top of my lemon bars consists of around (depending on recipe): 4 eggs, 300g sugar, juice of 2-3 lemons, zest and 55g flour.