Preheat oven to 350 degrees. Line a 9x13-inch baking pan with parchment paper, leave a little overhang to lift bars out easily.
In a small bowl, whisk together the flour, baking soda, salt and oats then set aside.
In a mixing bowl with paddle attachment, cream together the butter, peanut butter, brown sugar and sugar until fluffy and light in color. About 2 minutes.
Add in the vanilla, egg and egg yolk. Blend together and scrape down the sides of the bowl.
Add the dry ingredients into the wet then mix till combined.
Add the chocolate chip bars, chocolate chips and m&m's, blend until mixed in.
Press batter into the prepared pan. Top with a few of the chocolate chip bars, chocolate chips and m&m's.
Bake for 14-16 minutes or until edges lightly brown. Bars may look pale and slightly underdone in the middle and that's okay!
Let bars cool in baking pan for 20-30 minutes.
Cut into squares and enjoy!!!
Notes
You can add nuts, or any type of chocolate that you like to make this recipe your own.