Preheat the oven to 350℉ and line a baking sheet with parchment paper.
Whisk together the flour, salt, baking powder, and baking soda in a medium bowl until well combined. Set aside.
In the bowl of a stand mixer or with a hand mixer, beat the shortening and softened butter together until homogeneous. Add the light brown sugar and granulated sugar to the bowl and cream together for 3-4 minutes until light and fluffy.
Add the eggs, light corn syrup, molasses, and vanilla, mixing until well combined (the batter may look split, but this is normal). Pour in the dry ingredients, oats, and chocolate, stirring until a dough forms and there are no streaks of flour. At this point, the cookie dough can be refrigerated for up to 48 hours or can be scooped and frozen.1
For large, Chick-Fil-A style cookies, portion out the cookie dough into ¼ cup balls (you can also use a smaller cookie scoop for regular-sized cookies). Place the cookies 2'' apart on the prepared baking sheet. Bake for 11-13 minutes, rotating the pan halfway through, until the cookies are set and golden around the edges. Larger cookies may need longer in the oven, but do not overcook!
Once baked, immediately top the cookies with flaky salt and let cool. The cookies are best the day of but will last for 3 days stored at room temperature.