Use firm lemons that aren't overly juicy to prevent your cookies from going soggy.
Slice the lemons as thinly as possible for this recipe. Using a mandolin
is perfect for this. Also I suggest drying the lemon slices between 2 sheets of paper towel before baking.
If where you live is humid the brûlée topping with melt in the humidity so I suggest only baking as many cookies as you plan to eat in a day.