Crumble the Graham Crackers: Break up the crackers and place them in the bowl of a food processor along with the sugar, if using. Pulse to break the crackers further and then process continuously until the crackers are crushed into fine crumbs. Alternatively, place all the crackers in a plastic bag and crush with a rolling pin until broken into fine crumbs. You should end up with about 2 cups total of graham cracker crumbs.
Combine with Butter: Transfer the graham crackers to a bowl. Melt the butter and pour over the graham crackers. Stir until the crumbs are evenly coated and look wet. The crumbs should hold together in a clump if you press them in your fist; if not, add water a tablespoon at a time until this happens.
Press into a Pie Pan: Heat the oven to 375° F. Pour the crumbs into a 9-inch pie pan and press them evenly along the bottoms and sides.
Bake the Crust: If you are making a no-bake pie, like Ice Cream Pie, pre-bake the crust for 8 to 10 minutes until dry and fragrant. Cool completely before proceeding with the recipe. For a baked pie, like pumpkin or custard pie, fill the pie and bake according to the recipe instructions.
