Directions:

1. Preheat oven to 375°F. Line a 18 x 13 sheet pan with parchment paper.
2. Using a stand mixer fitted with the paddle attachment, cream butter and brown sugar for 3-5 minutes until light and fluffy. Add vanilla and mix for 1 minute. Add eggs one at a time scraping down the sides of the bowl after each egg.
3. In a small bowl mix the cocoa powder, cornstarch, flour, salt, baking soda and chocolate chips.
4. Slowly add the dry ingredients and mix until just combined.
5. Transfer the cookie dough onto the prepared sheet pan. Use a flat spatula or the back of a spoon to level the cookie dough. Bake in preheated oven for 12-14 minutes.
6. Allow the cookie to fully cool for 45 minutes.
7. Transfer the cookie to a cutting board and cut in half to make two even rectangles.
8. Scoop all the ice cream that has been thawing onto one half of the cookie. Again, use a flat spatula or the back of a spoon to make an even layer of ice cream on the cookie. Top the ice cream with the remaining cookie, top side up. Freeze for 20 minutes.
9. Remove giant ice cream sandwich cookie from freezer and transfer to a cutting board. Cut the sandwich into 12 even pieces. Dip the exposed ice cream into your toppings of choice. Freeze until ready to eat. Enjoy!