Mix together the softened butter, 1/2 cup of peanut butter, and brown sugar until smooth and creamy. Add in the egg and vanilla. Then, mix in the all-purpose flour until combined. Fold in the peanut butter chips, white chocolate chips, and 1/2 cup mini chocolate chips. Spread the batter into the prepared pan and bake for 22-25 minutes until the edges turn brown and the middle is set.