Heat the oven to 350°F (175°C). Fit parchment paper into an 8-inch square baking pan, letting extra paper extend above the sides for lifting later.

Stir the flour, packed light brown sugar, and salt together in a medium bowl. Work in the cold butter cubes with a pastry cutter or your fingers until you have a coarse, crumbly mixture. Press it evenly across the bottom of the prepared pan, then bake for 15 minutes, or until pale golden.

During the crust’s baking time, whisk the corn syrup, granulated sugar, eggs, vanilla extract, and melted butter into a smooth mixture. Fold in the chopped pecans so they are spread throughout.

Take the baked crust out of the oven and immediately add the pecan mixture on top. Gently spread the filling into an even layer if necessary.

Place the pan back in the oven for 20–25 minutes. The filling should look set and a little puffed, with a gentle jiggle in the middle rather than a liquid center.

Set the pan on a wire rack and let the bars cool completely. Use the overhanging parchment to lift them onto a cutting board, then cut into 9 squares.

For an optional finishing touch, lightly dust the bars with powdered sugar before serving.