Grease an 8-inch (20cm) square pan with butter and line with parchment paper.
Preheat the oven to 350°F / 180°C / Gas Mark 4, no fan (if you have a convection oven reduce the temperature by about 20° or follow the manufacturer's instructions).
If you've purchased whole graham crackers and not graham cracker crumbs, you need to pulse them in a food processor with sugar until crumbs form.
Add the cookie crumbs, salt, and melted butter into the pan. Stir with a spoon until all the crumbs are coated in butter.
Press the mixture firmly into the bottom of the pan. I like to start with a spoon and then press the crumbs with the bottom of a measuring cup.
Bake the crust for 10-12 minutes or until golden.
Chill the crust for 10 minutes before filling.