Preheat oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper, leaving overhang on sides for easy removal.
For the crust, combine flour, sugar, and salt in a food processor. Add cold butter cubes and vanilla, pulsing until mixture resembles coarse crumbs and begins to come together.
Press dough evenly into prepared pan and bake for 15-18 minutes until lightly golden. Remove from oven but keep it on.
While crust bakes, whisk eggs, brown sugar, corn syrup, melted butter, vanilla, and salt until smooth. Stir in chopped pecans and cinnamon if using.
Pour filling over hot crust and arrange pecan halves decoratively on top. Bake for 25-30 minutes until filling is set but still slightly jiggly in center.
Cool completely on a wire rack before refrigerating for at least 2 hours. Use parchment overhang to lift out, then slice into bars.