Place the peanut butter crackers in a food processor and pulse until finely crushed. Alternatively, place them in a zip-top bag and crush with a rolling pin.
In a medium bowl, combine the crushed crackers and sugar. Pour the melted butter over the mixture and stir until all crumbs are moistened.
Transfer the mixture to a 9-inch pie plate. Press firmly and evenly into the bottom and up the sides using the bottom of a measuring cup or your fingers.
Refrigerate for at least 1 hour before filling, or freeze for 15 minutes for a firmer crust.
Tips
For a gluten-free version, use gluten-free peanut butter crackers.
This crust can be baked at 350°F for 10 minutes if you prefer a crisper texture, but it's not necessary.
Store any leftover crust in the refrigerator for up to 3 days.