Preheat your oven to 350 degrees F. Line a cookie sheet with a silicone mat or parchment paper and set aside.
Beat the shortening, peanut butter, and brown sugar together in a large bowl until smooth. Add the pudding mix, eggs, egg yolk, and vanilla. Beat for 1 minute on medium speed.
In a separate bowl, combine the flour, baking soda, and salt. Add the dry ingredients to the wet ingredients 1/2 cup at a time, mixing between each addition until just combined.
Use a medium cookie scoop to portion the cookie dough. Roll the dough into balls between your palms. If you like, roll the dough balls in granulated sugar – this is optional.
Place the balls of dough on the prepared cookie sheet about 2 inches apart. Use a fork to gently press the dough balls flat, making two indents with the fork tines in a criss-cross pattern.
Bake for 9 to 12 minutes. Then let the cookies rest on the baking sheet for 2 minutes before transferring them to a wire rack to cool completely.
Notes
Do not use all-natural peanut butter in this recipe.
Butter can be used in this recipe instead of shortening but I find that it makes them less chewy overall. The butter-flavored shortening gives the buttery flavor everyone loves and yields the best texture.