Preheat oven to 350F, middle rack. Line a baking sheet with parchment. In a food processor pulse 2/3-1 cup of crackers to make 1/3 cup cracker powder. Set aside.
In the bowl of a stand mixer cream the butter, peanut butter, and brown sugar until well blended. Add in the egg and egg yolk, mix until incorporated.
Turn on the mixer and slowly add in the flour, cracker powder, salt, baking soda, and baking powder. Take the remaining crackers and crush them by hand into small chunks/pieces and place them in the mixer. Turn the mixer on low to incorporate.
Slowly add in the milk. You want a dough that will hold a shape when scooped. It should be moist but not wet. Add in the chocolate chunks and just mix until combined. Do not over mix as you do not want to break up the chocolate or the crackers anymore. Using a medium-size cookie scoop (or a spoon) out a 1” size ball. Gently roll the ball in your hand – again you want a mixture that holds together. Place on the cookie sheet 1 1/2” apart and press down slightly. These cookies won’t spread out much. Bake for 8-9 minutes or just until golden brown. The cookies will be soft but will tighten up upon cooling. Place on a cooling rack to cool completely.