Line an 8×8 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
In a large mixing bowl, beat the softened unsalted butter and creamy peanut butter together until smooth and creamy using a hand mixer or stand mixer.
Add the brown sugar and granulated sugar to the peanut butter mixture and beat until combined and fluffy.
Mix in the vanilla extract.
Gradually add the all-purpose flour and salt to the wet ingredients, mixing on low speed until fully incorporated and a dough forms.
Fold in the mini chocolate chips evenly throughout the dough.
Press the dough evenly into the prepared baking pan, smoothing the top with a spatula.
Refrigerate the bars for at least 1 hour or until firm.
Once firm, lift the bars out of the pan using the parchment paper overhang and cut into 12 equal-sized bars.
Store the bars in an airtight container in the refrigerator.