Preheat oven to 350 degrees. Line two baking sheets with parchment paper.
Cream butter, shortening, sugar, and brown sugar until light and fluffy.
Beat in egg until incorporated.
Mix in vanilla and peanut butter until smooth and uniform. Scrap bowl.
Sprinkle in flour, baking soda, salt and chocolate chips (if applicable) to peanut butter mixture, beating until just combined. Dough should look uniform in color but fall apart when touched.
Drop cookie dough by the tablespoon full with a small cookie scoop and flatten with a fork in a cross hatch pattern.
Bake cookies for 12-15 minutes until they're barely browned around the edges. Remove from oven and cool on rack.