Preheat oven to 350 degrees. Spray an 8-inch square baking dish with nonstick spray and set aside.
Using an electric or stand mixer, cream together peanut butter, butter, sugar and brown sugar until light and fluffy, about 3 minutes on medium-high speed. Add the egg, milk and vanilla extract and continue beating until combined.
Add the flour, baking soda and salt, and beat slowly until incorporated. Increase speed to medium-high and beat another minute.
Fold in chocolate chips.
Spread batter evenly in the prepared pan.
Bake 25-30 minutes until edges are just turning golden brown and a toothpick inserted into the center comes out clean. Let cool completely, then cut into 16 bars and serve!
Recipe by Flying on Jess Fuel at https://www.jessfuel.com/chocolate-chip-peanut-butter-blondies/