Preheat your oven to 450 degrees.
Place your rolled out puff pastry on a parchment lined baking sheet.
Fold all sides of pastry in one inch and prick all over with a fork.
Bake for 20 minutes or until golden brown.
In a food processor add your sugar and the zest of two lemons and pulse until finely minced.
In a bowl cream your butter then add the lemon and sugar mixture
add eggs one at a time mixing in each one,
add lemon juice and salt and mix well.
Pour into a 2 quart sauce pan and heat on low until thickened, stirring constantly
When thickened place into the refrigerator for 1 hour to cool.
Spread cooled mixture on top of the cooked puff pastry slice and serve for a delicious summer treat.