Preheat your oven to 350°F. Lightly coat an 8x8-inch baking pan with cooking spray. Line the pan with parchment paper, letting it hang over the sides for an easy lift.
To prepare the crust, beat the butter at room temperature with granulated sugar and salt until smooth. Mix in 1 cup of all-purpose flour until a crumbly dough forms. If the dough appears too dry, add a splash of water to reach the right moisture level. Sprinkle some flour on your hands and press the dough evenly into the pan.
Bake the crust for 20 to 22 minutes until the edges turn golden brown.
Meanwhile, make the filling by whisking together corn syrup, brown sugar, eggs, 2 tablespoons of flour, salt, and vanilla extract in a bowl. Stir in the pecan pieces.
Once the crust is baked, remove the pan from the oven and immediately pour the filling over the hot crust. Spread evenly and return to the oven for 25 to 30 minutes, or until the filling is set and has a dark golden color.
Remove the pan from the oven and let it cool completely on a wire rack. Then, refrigerate for at least 1 hour before cutting into 12 bars.