Combine graham crackers in the bowl of a food processor.

Pulse until all large pieces are broken and the crackers are all crumbly.

Remove lid.

Add the sugar and melted butter and cinnamon, if using.

Pulse several more times and stop to scrape the sides of the bowl one or two times.

Pour crumb mixture into a pie plate.

Using the back of a glass or a tarte tamper to help pack the crust.

Don't overfill if you're using a smaller size pie plate because the pie filling may run out.

Bake at 375 for 8-10 minutes.