In a large bowl, cream together the butter, peanut butter, brown sugar, and white sugar until smooth.
Next, beat in the egg and vanilla. Mix until the dough is light and fluffy.
In a separate bowl, whisk together the flour, baking soda, and salt. Slowly stir the dry mixture into the wet ingredients until just combined.
Fold in the chocolate chips.
Chill the dough for 30 minutes in the fridge. It helps the cookies keep their shape and makes them even chewier.
Scoop the dough into balls about 1 to 1.5 tablespoons each and place them 2 inches apart on the baking sheet
Bake for 9–11 minutes, or until the edges are lightly golden and the centers still look slightly soft.
Let them rest on the baking sheet for 5 minutes before moving to a wire rack.