Prepare a 20 centimeters square pan with parchment paper.
Grind or smash the cookies until it resembles fine crumbs.
Mix the crumbs + melted butter + brown sugar and press it on the bottom of the prepared pan. Bake at 175 C for 13-15 minutes
Let it cool for 30 minutes.
Mix the egg yolks and zest for about 5 minutes in a large bowl until they thicken.
Add the condensed milk and mix for 3 minutes.
Whisk in the lime juice.
Pour this mixture over the cooled base and bake at 175C for 15 minutes. Let it cool for 30 minutes then place it in the fridge overnight. Beat the whipping cream and sugar until firm peaks show.
Spread on top of the custard and garnish with more lime zest.