Whisk the flour, cornstarch, and salt together in a small bowl. Set aside.
Add butter and creamy peanut butter to a large mixing bowl. Beat on medium speed until
creamy. Add in the powdered sugar, beating on medium speed until the combination is light and fluffy.
Use a rubber spatula to scrape down the sides of the mixing bowl.
Divide the flour mixture into three equal parts. Beat on medium-low speed as you add in one-third of the flour mixture. Continue to beat after each addition until each addition is completely blended.
Scrape the sides of the bowl then roll into a ball. Cover the bowl of dough with plastic wrap.
Put in the refrigerator for one hour.
Preheat the oven to 350 degrees.
Line a cookie sheet with parchment paper
With a one-inch cookie, scoop make cookie balls. Using your hands make the batter into tight
balls. Put each cookie ball on the lined sheet two inches apart. Press the cookie ball gently using the bottom of a glass.
Bake at 350 degrees for 11-13 minutes or until the edges of the cookies are slightly browned.
Remove the cookie sheets from the oven. Set aside to cool slightly. Transfer the cookies to a cooling rack. Set the cookies aside to cool completely before topping.