Chocolate Chip Cookie Dough Sandwiches
- In a large bowl using a handheld mixer or stand mixer fitted with a paddle attachment, beat the butter, and both sugars together on medium speed until combined and creamy, about 2 minutes. Beat in the egg and vanilla. Scrape down the sides and bottom of the bowl as needed.
- In a separate bowl, whisk flour, cornstarch, baking soda, and salt together. Add the dry into the wet ingredients, then beat on low speed until combined. The cookie dough will be slightly thick. On low speed, beat in the chocolate chips.
- Cover dough tightly and chill it in the refrigerator for at least 1 hour and up to 3–4 days. Chilling is imperative for this cookie dough.
- While the cookie dough is chilling, make the frosting: In a large bowl using a handheld mixer or stand mixer fitted with a paddle attachment, beat the butter on high speed until creamy, about 1 minute. Add the brown sugar. On medium speed, beat until combined, scraping down the sides and bottom of the bowl as needed. Add the vanilla, flour, and salt and beat on low speed until everything is mixed. The mixture will be thick and heavy. Add the milk and beat on low for 30 seconds, then switch to high and beat for at least 2 minutes until combined and creamy. Gently fold in chocolate chips. Set aside at room temperature until ready to use.
- Remove cookie dough from the refrigerator and allow to sit at room temperature for 10 minutes. Preheat oven to 350°F (177°C). Line 2 large baking sheets with parchment paper or silicone baking mats. Set aside.
- Once chilled, the dough will be slightly crumbly, but will come together if you work the dough with your hands as you roll into individual balls. Scoop out the dough and roll into balls, about 1 Tablespoon of dough each. Bake for 8–10 minutes, until barely golden brown around the edges. They will look extremely soft when you remove them from the oven.
- Allow to cool for 5 minutes on the cookie sheet. If the cookies are too puffy, try gently pressing down on them with the back of a spoon. They will slightly deflate as they cool. Transfer to cooling rack to cool completely before sandwiching.
- Sandwich dollops of cookie dough frosting between two cooled cookies, creating sandwiches.
- Cover and store leftover cookie sandwiches in the refrigerator for up to 5 days.
