While living in the San Francisco Bay Area, one of my favorite nostalgic desserts were ice cream sandwiches. In my opinion, the best ones are sandwiched with slightly warm cookies, so it always feels like you are eating freshly baked cookies. I am recreating that experience in this recipe with decadent chocolate cookies that have a gooey crunchy peanut butter filling.
Using a 1-tablespoon ice cream scoop, scoop the peanut butter into 12 mounds onto a small baking pan lined with parchment paper. Make sure they are rounded on top and no bigger than the circumference of a quarter. Freeze until frozen solid, 35 to 40 minutes.
Combine the butter, both sugars, and cocoa powder in a stand mixer fitted with the paddle attachment and cream on low speed until light and fluffy, 2 to 3 minutes. Stop and scrape the bowl. Whisk the egg with the coffee extract in a small bowl. While the mixer is running on low speed, add the egg mixture and mix just until incorporated. Stop and scrape the bowl.
Stir together the flour, cornstarch and baking soda in another small bowl. Add it to the stand mixer and mix on low speed until incorporated. Stop and scrape the bowl. Mix briefly until all of the dry ingredients have been fully incorporated. Add the milk and chocolate chips. Mix to combine.
Scoop the dough into 12 mounds, each 3 tablespoons (1.5 ounces), on a sheet pan lined with parchment paper. Place in the freezer for 25 minutes.
Position racks in the upper and middle thirds of the oven and preheat to 350 degrees F.
Remove the cookie dough and peanut butter from the freezer. Flatten 1 of the cookies with the palms of your hands, place 1 mound of peanut butter in the center then wrap the dough around it until fully enclosed in a ball of cookie dough. Repeat with the remaining dough and peanut butter. Please work swiftly before the peanut butter gets soft. If so, return the peanut butter to the freezer.
Divide the dough among 2 sheet pans lined with parchment paper (6 cookies on each). Sprinkle with the fleur de sel.
Bake on the upper and lower racks for 10 minutes. Rotate the sheet pans and bake 4 to 5 minutes. Allow the cookies to cool on the sheet pans for 15 minutes.
Sandwich the cookies with ice cream and serve immediately.