PREP TIME: 40 MINS
COOK TIME: 13 MIN
Heat oven to 350 degrees F (176 degrees C). Line a baking sheet or 2 if you have 2, with silicone baking mats (ungreased) and set aside.
In a medium mixing bowl, whisk together the dry ingredients, the flour, and the kosher salt, until combined.
In a large mixing bowl, using a handheld electric mixer (or by hand), mix the shortening, unsalted butter, brown sugar, egg yolk, and vanilla extract, until evenly combined.