Preheat oven to 350 degrees F. In a bowl mix together dry ingredients.
In another bowl beat together the butter and peanut butter together until smooth. Then add sugars and beat until creamy.
Add egg and egg yolk and vanilla. Beat for 30 seconds together. Slowly incorporate dry mixture until batter is smooth. If you want to add chocolate chips fold them in now.
Use a cookie scoop so they are all the same size and place on a lightly sprayed cookie sheet or baking sheet with parchment or a silpat sheet on top.
Use a fork to gently press down twice on each one, with tines facing opposing directions on each press so they are crossed and batter it a bit flattened.
Bake for 8 minutes in a preheated oven. Remove and keep on baking sheet until completely cooled to create a very moist fall apart with a little crisp on the edges cookie.