Instructions

• Preheat the oven to 350°F (175°C). Line baking sheets with parchment paper or silicone baking mats, or lightly grease them.
• In a large mixing bowl, combine the cold cubed butter and the packed light brown sugar. Beat with a stand mixer or hand mixer until the mixture is light and fluffy (this will take longer than with room-temperature butter). Scrape down the bowl as needed.
• Add the smooth peanut butter, vanilla extract, and eggs to the butter–sugar mixture. Mix until smooth and fully combined.
• In a separate bowl, whisk together the all-purpose flour, cornstarch, salt, baking soda, and baking powder.
• Add the dry ingredients to the wet ingredients in two additions, mixing on low speed or stirring with a spatula until just combined. The dough will be fairly dry and firm.
• Fold in the white chocolate chips and the chopped frozen white chocolate peanut butter candies (if the candies are not already chopped, coarsely chop them before adding).
• Scoop or drop dough by spoonfuls (to make about 1 1/2" cookies) onto the prepared baking sheets, spacing the cookies about 2 inches apart. The dough is firm and the cookies will not spread much while baking.
• Bake for 9–12 minutes, or until the edges start to turn slightly brown and the centers are set.
• Remove the baking sheets from the oven and let the cookies cool on the sheets for about 5 minutes. Transfer the cookies to wire racks to finish cooling.
• Store cooled cookies in an airtight container. Makes approximately 4 dozen cookies, about 1 1/2" in diameter.