Mix flour and salt in a large bowl. Cut in shortening using a pastry cutter. Cut in butter until the particles are the size of small peas.
Combine the milk and lemon juice in a small bowl.
Add oil and milk/lemon mixture to the flour mixture and stir until a soft dough forms. You may need to use your hands to form the mixture into a dough.
Flatten the dough into a disc and wrap it with plastic. Refrigerate while you make the pie filling (30-45 minutes).
Whisk eggs in a large mixing bowl. Add sugars, corn syrup, melted butter, and salt.
Stir in roughly chopped pecans.
Roll the pie crust on a lightly floured surface. Keep rolling until it is about a 13x18" rustic-looking rectangle.
Place the rectangle into a 10×15″ jelly roll pan, allowing the excess to hang over the edge of the pan.
Tuck the excess pie crust into the pan (rolling it forward or behind to tuck into place). Pinch or crimp to finish the edge.Brush the edge of the pie crust with an egg wash (1 egg mixed with 1 Tbsp. water)
Preheat oven to 350 degrees.Lower the baking rack to the bottom ⅓ of the oven. If you have a pizza stone, place it on the oven rack to preheat.
Pour pecan pie filling into the prepared crust.
Bake the slab pie for 30 minutes in preheated oven.
Cover/tent loosely with foil and bake for an additional 20 minutes.Note: The pecan pie filling is quite sticky. You can spray the bottom of the foil with non-stick spray to prevent it from sticking when you tent it. I don't generally do this, but it might be helpful for some.
Allow the pie to cool for at least 2 hours before slicing.
Video
Notes
Storage: Store leftover pie in the refrigerator for up to 4 days.Baking Sheets: I only bake on light-colored baking sheets. If you bake on dark sheets, you may need to adjust the baking time.Jelly Roll Pan: This recipe is formulated for a standard 10"x15" jelly roll pan.