Add flour, sugar, corn starch, salt and cold diced salted butter to a food processor. Pulse several times.
Add vanilla to the food processor and pulse again several times until everything is incorporated.
Put shortbread mixture in an 8x8 parchment lined pan and squeeze the shortbread mixture together with your hands several times. The heat from your hands will soften everything and it will bring it all together.
Press into the bottom of the plate and bake on 325 for 25 minutes.
While the crust bakes, make your filling. Measure pecans and then roughly chop. Set aside.
To a mixing bowl add brown sugar, eggs, vanilla and corn starch. Whisk. Add light corn syrup, cinnamon, heavy whipping cream and salt. Whisk again.
Fold in pecans.
Add mixture to the hot shortbread crust. Place back in the oven for another 50 minutes. Remove from oven and check for doneness. Jiggle the pan, you want the center to move a little when you shake it, but the edges to be fully set.
Let rest on the counter for at least 2 hours. Once cooled to room temperature place in the fridge for at least 2 hours. The longer it can sit in the fridge the better. Cut and serve.