Foamy cakey layer on top of lemon squares 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.
I make my lemon squares the same way and get this top.  I haven't noticed it effects the end result.  I lowered my oven temp a bit to help with it, and it doesn't eliminate it, but it's thin and not overly browned.  And once the powdered sugar is on top, no one is any wiser.

The only way I've seen to not have this is to do a stove top version that's finished in the oven.