Pre-heat oven to 350 degrees.
On a baking sheet, toast pecans for about 10 minutes at 350 degrees, until fragrant and just beginning to darken, tossing once. Let cool.
In a food processor, process pecans until they're the consistency of coarse meal. Add flour, sugar, salt, and cinnamon to the food processor and pulse just to combine.
Add chilled butter pieces and pulse until the mixture resembles coarse meal with a few pea-size pieces.
Transfer dough mixture to a large bowl and drizzle 4 T of ice water over the Dough. Mix, adding another tablespoonful of water if needed, just until mixture comes together.
Form the dough into a 6"-diameter disk. Wrap the disc in plastic and place in the refrigerator to chill for at least 1 hour.
Do Ahead: Dough can be made 2 days ahead. Keep chilled, or freeze up to 1 month.