Preheat the oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper, leaving enough overhang on the sides to lift the bars out later.
In a food processor, combine the all-purpose flour, packed brown sugar, and cold cubed butter. Pulse until the mixture resembles coarse, sandy crumbs. (Alternatively, use a pastry blender in a bowl).
Pour the crumb mixture into the prepared baking pan. Press the crust firmly and evenly across the bottom. Bake for 15 minutes until lightly golden.
While the crust is baking, whisk together the eggs, light corn syrup, white sugar, melted butter, and vanilla extract in a large bowl until smooth.
Stir the chopped pecans into the wet filling mixture.
Carefully remove the hot crust from the oven. Immediately pour the pecan filling evenly over the hot baked crust.
Return the pan to the oven and bake for 20-25 minutes, or until the filling is puffed, bubbly, and no longer jiggles in the center.
Cool completely in the pan on a wire rack. Once cooled, use the parchment overhang to lift the slab out and cut into 16 bars.