Instructions

1. Combine flour, 1 tbsp. sugar, and salt in a food processor; pulse to combine. Add 12 tbsp. butter; pulse until pea-size pieces have formed. Drizzle in 3–4 tbsp. ice water; continue pulsing until dough just comes together. Turn dough onto a floured surface; knead briefly into a ball. Divide dough in half, form into 2 disks, and wrap tightly in plastic wrap. Chill for at least 1 hour or overnight.
2. Put remaining sugar, cream of tartar, and 1 3⁄4 cups water into a medium saucepan; bring to a boil. Reduce heat to medium-low; simmer for 15 minutes. Remove from heat; add lemon juice, lemon zest, and cinnamon. Let syrup cool to room temperature.
3. Heat oven to 400°. On a floured surface, roll 1 dough disk into a 12" circle, transfer to a 9" pie pan, fill with crackers, and pour syrup over top. Dot mixture with remaining butter. Roll out remaining dough into an 11" circle and place on top of pie; trim dough, leaving a 1⁄2" overhang. Fold edges up over rim; press to seal. Decorate edge of the pie dough with the tines of a fork. Cut 6 slits in the top of the pie, brush with the egg, and bake until crust is golden brown, about 35 minutes. Let pie cool completely before slicing.