Preheat your oven to 350°F (175°C). Lightly spray a 9x13-inch baking dish with cooking spray to ensure the bars don't stick.
Unroll the can of crescent dough and press it evenly into the bottom and about 1/2 inch up the sides of the prepared baking dish. Be sure to firmly press together any perforations in the dough to create a seamless crust. Prebake the dough in the oven for 8 minutes so it partially sets and won't become soggy once the filling is added. I’ve found that prebaking helps keep the crust crisp.
While the crust bakes, combine the chopped pecans, granulated sugar, light corn syrup, melted butter, vanilla extract, and egg in a medium bowl. Stir until well blended, ensuring all the ingredients are fully incorporated to make a smooth filling.
Pour the prepared pecan filling evenly over the partially baked crust from Step 2. Return the dish to the oven and bake for an additional 18 to 22 minutes, or until the filling is set and the bars are golden brown on top.
Remove the baking dish from the oven and allow the bars to cool completely, which should take about 1 hour. Once cooled, cut into bars for serving. For a clean cut, I like to use a sharp knife wiped clean between slices.