For the crust, blend the butter cookies until they become small crumbles. Add the butter (melted) to the mix and blend. You might need to adjust the butter amount to make sure the crumb is sticking together a bit, but did not become a dough yet.
Put the crumbs in the bottom and the sides of the mold, and press it to make it compact. Leave it aside, and prepare the filling.
Preheat the oven for 180C and bake the crust for 15 minutes. You can cover it up with tin foil and add some weight on top to prevent the crust from cracking.