Wash hands with soap and water for 20 seconds.
Do not taste or eat any raw dough or batter made with uncooked flour and/or raw eggs.
Preheat oven to 350°F. Line a 9 x 9-inch baking pan with parchment paper.
To the melted butter, add the sugar, vanilla, and flour until a thick, sticky dough forms.
Transfer the crust mixture to the prepared pan and press firmly with a silicone spatula or fingers into an even layer over the pan bottom.
Bake the crust 10-15 minutes or until lightly golden.
In a large bowl, with an electric mixer, beat eggs, brown sugar, corn syrup, and flour until combined. Scrape sides of the bowl as needed. Fold in chopped pecans.
When the crust is done, remove it from the oven and pour the filling over the crust to cover the entire surface.
Bake the bars for 30-35 minutes or until the top is golden brown and crispy.
Remove from the oven and allow bars to cool on a wire rack to room temperature. If desired, chill in the refrigerator to make slicing easier.
Wash hands with warm running water and soap after handling uncooked flour and/or raw eggs. Clean all surfaces and utensils they have touched.
To cut, remove the baked bars out of the pan and onto a cutting board. Loosen the paper from the edges, then cut with a sharp knife into squares.
Cover the pan with a lid, foil, or plastic wrap. If you don’t keep the bars in their original pan, slice them and place them in an airtight container. To stack, separate layers with a sheet of parchment or wax paper.
Freeze for longer storage.