Place a parchment paper on a 10x10x2 square cake pan. Spray it with Pam then set aside. Preheat oven to 350°. In a bowl, combine flour, baking powder, and salt. Set aside.
Cream butter, sugars, eggs, peanut butter, and milk until well combined. Gradually add flour baking powder, and salt into the mixing bowl.
Divide batter in two. In one half stir in cocoa powder and chocolate chips.
Using an ice cream scooper, scoop the chocolate batter into the pan, with spaces in between. Refer to the picture.
Do the same thing with the plain batter. Refer to the picture.
With a butter knife, run a swirly pattern into the batter.
Bake it in the oven for 30-35 minutes.
Cool completely before cutting into squares.
