Preheat oven to 375 F. Line 3 baking sheets with parchment paper, if desired, and set aside.
Combine flour, ½ cup sugar, brown sugar, baking soda, and salt in a stand mixer fitted with the paddle attachment and turn to low; mix for 1 minute.
To the stand mixer bowl, add the coconut oil, peanut butter, milk, vanilla, and egg. Mix on medium speed for 1-2 minutes or until well-incorporated.
Roll the dough into 1 inch balls and roll in the remaining 2 tablespoons sugar; place on baking sheets spaced 2 inches apart. Bake cookies for 10-12 minutes; remove and immediately insert a kiss into the middle of each cookie, pressing firmly. Allow to cool completely.