Preheat oven to 375 degrees F and grease 6 mini tart shells.
Crush graham crackers in a food processer or put the crackers in a plastic bag and crush with a rolling pin. Make sure there are no large pieces.
Combine graham crackers, sugar and butter in a bowl and mix until well combined.
Evenly divide between the 6 tart shells and press the mixture into each shell with a spoon.
Place tart shells on a baking tray and bake for 7 minutes. Allow to cool and then place in the freezer for 15-20 minutes to harden up.