Preheat the oven to 350 degrees Fahrenheit and line a baking sheet with parchment paper.
Cream together the butter, peanut butter, granulated sugar, and brown sugar in a large bowl until light and fluffy.
Add the egg and vanilla extract to the peanut mixture; mix until just combined.
Whisk together the flour, baking soda, baking powder, and salt in a separate bowl, then add to the wet mix and stir until combined. Fold in the chocolate chips.
Repeat the same mixing process for the chocolate dough: creaming the butter and sugars, then egg and vanilla, then dry ingredients with cocoa powder, and fold in chocolate chips.
Chill both doughs for at least 30 minutes in the refrigerator.
Scoop about 1 tablespoon of each dough, squish together, and roll into a ball. Swirl gently for a marbled look.
Place on prepared baking sheet, spacing about 2 inches apart.
Bake for 9–12 minutes, until edges are set and tops begin to crack.
Let cookies cool on the pan for 5 minutes before transferring to a rack to cool completely.
Notes
To maintain softness, store with a slice of bread in an airtight container for up to 5 days, or freeze in a sealed bag for longer storage.