Preheat oven to 350F and lightly grease a 12-cup muffin pan. Set aside.
Place butter and sugars in the bowl of a large stand mixer, fitted with a paddle attachment OR in a large mixing bowl with a wooden spoon. Mix on medium speed or by hand until creamy, about 2 minutes. Add peanut butter, egg, and vanilla and mix until smooth.
In a small bowl, combine flour, baking soda, and salt. Mix flour mixture into peanut butter mixture until dough is just combined. Fold in chocolate chips.
Divide dough into 12 pieces and pat into prepared muffin cups. Bake cookie cups at 350F 10-15 minutes until edges are lightly browned.
Allow cookie cups to cool in pan 20 minutes then transfer to a wire cooling rack to cool completely. Enjoy!