Move oven rack to lowest position in your oven, and preheat to 350 degrees.  Tear two aluminum foil sheets off of your roll (one about 13 ins, and the other 9 ins).  Lay the longer sheet in the baking pan, pushing foil into corners.  Then lay second piece perpendicular to the first piece.  Lightly spray the foil with cooking spray.  You've just created a foil sling.  This will help with removal of bars from pan after cooking.

Whisk flour, sugar and salt together in medium bowl.  Add melted butter, and stir with wooden spoon, until a dough begins to form.  With your hands, mix the dough together, until the flour is completely incorporated, and when you squeeze a handful of dough, it stays together a bit.

Spread tablespoon size bits of dough all over pan and push down with your fingers and palm of your hand, until the bottom of pan is evenly covered with the crust.

In a medium bowl, whisk sugar, corn syrup, melted butter, vanilla, and salt together, until smooth (about 30 seconds).  With a spatula, fold pecan halves into sugar mixture, until evenly coated.

Pour topping over crust, using a spatula to spread evenly over crust.  Bake in preheated oven for 23-25 minutes, or until topping is evenly spread and bubbling rapidly.

Transfer pan to wire rack.  Cool bars in the pan for 1 ½ hours.  Pull bars out of pan using foil sling.  If you want to add the optional flake sea salt, this is the time to do it.  Cut into squares on a cutting board.  Serve and Enjoy!!!  Store in Airtight container.