1 large egg 1/2 cup unsalted butter (1 stick), softened 1/2 cup granulated sugar 1/2 cup light brown sugar, packed 2 teaspoons vanilla extract 1 3/4 cups cake flour (no substitutions, I used Swans Down) 2 teaspoons cornstach 1/4 teaspoon baking powder 1/4 teaspoon baking soda pinch salt, optional and to taste one 10-ounce bag Reese’s Peanut Butter Chips (about 1 2/3 cups) Peanut Butter Frosting 1/3 cup creamy peanut butter (use Jif, Skippy, etc. Not homemade or natural PB because they’ll separate and so will the frosting) 1/4 cup unsalted butter (half of 1 stick), softened 1 1/2 cups confectioner’s sugar pinch salt, optional and to taste splash cream or milk, if needed to achieve proper consistency (I used about 1 1/2 tablespoons cream) chocolate sprinkles, optional for garnishing DIRECTIONS: For the Cookies – To the bowl of a stand mixer fitted with the paddle attachment (or large bowl and electric hand mixer), cream together the first 5 ingredients (through vanilla) on medium-high speed until light and fluffy, about 5 minutes. Stop, scrape down the sides of the bowl, and add the next 5 ingredients (through optional salt), and mix on low speed until just incorporated, about 1 minute; don’t overmix. Add the peanut butter chips and mix until just incorporated. Dough will be on the sticky and tacky side. Using a medium 2-inch cookie scoop, form heaping two-tablespoon mounds (I made 13). Place mounds on a large plate, flatten mounds slightly, cover with plasticwrap, and refrigerate for at least 3 hours, or up to 5 days, before baking. Do not bake with warm dough because cookies will spread and bake thinner and flatter. Preheat oven to 350F, line a baking sheet with a Silpat or spray with cooking spray. Place mounds on baking sheet, spaced at least 2 inches apart (I bake 8 cookies per sheet) and bake for about 8 to 9 minutes, or until edges have set and tops are just beginning to set, even if slightly undercooked, pale and glossy in the center. Do not overbake because cookies will firm up as they cool. Allow cookies to cool on the baking sheet for about 5 minutes before transferring to a wire rack to finish cooking. Meanwhile, make the frosting. For the Peanut Butter Frosting – To the bowl of a stand mixer fitted with the paddle attachment (or large bowl and electric hand mixer), combine the peanut butter and butter, and beat on medium-high speed until light and fluffy, about 3 minutes. Slowly add the sugar, optional salt, and mix until frosting comes together. Add a splash of cream or milk as necessary to achieve desired consistency. Add a generous dollop (about 2 tablespoons) to each cookie, and smooth it as desired with a knife or spatula. Optionally garnish with sprinkles. Serve immediately. Cookies will keep airtight at room temperature for a few days or in the refrigerator for up to 1 week. I’m okay with leaving buttercream frosting at room temperature for a couple days; if you aren’t, refrigerate the cookies, knowing they’ll dry out more. Unbaked cookie dough can be stored airtight in the refrigerator for up to 5 days, or frozen for up to 4 months, so consider baking only as many cookies as desired and save the remaining dough to be baked in the future when desired.