Part 1: Making the Irresistible Cookie Dough

1. Prepare Baking Sheets: Line two to three large baking sheets with parchment paper or silicone baking mats. This prevents sticking and helps with even baking. Set aside.
2. Cream Butter and Sugars: In a large mixing bowl, using a hand mixer or a stand mixer fitted with the paddle attachment, beat the softened unsalted butter, granulated sugar, and packed light brown sugar together on medium speed until the mixture is light, fluffy, and pale in color. This process, called creaming, usually takes about 2-3 minutes. Scrape down the sides and bottom of the bowl occasionally to ensure everything is incorporated. This step is vital as it incorporates air, which contributes to the cookies’ texture.
3. Add Eggs and Vanilla: Add the room temperature eggs one at a time, beating well after each addition until fully incorporated. If the eggs are cold, they can cause the butter to seize. Beat in the pure vanilla extract until combined. The mixture should look smooth and emulsified.
4. Combine Dry Ingredients: In a separate medium bowl, whisk together the all-purpose flour, cornstarch, baking soda, and salt. Whisking helps to distribute the leavening agent (baking soda) and salt evenly throughout the flour.
5. Gradually Add Dry to Wet Ingredients: With the mixer on low speed, gradually add the dry ingredient mixture to the wet ingredient mixture in three or four additions. Mix only until the flour is just combined. Be careful not to overmix at this stage; overmixing develops gluten, which can result in tough cookies. A few streaks of flour remaining are okay, as they will get mixed in with the chocolate chips.
6. Fold in Chocolate Chips: Remove the bowl from the mixer (if using a stand mixer) and gently fold in the semi-sweet chocolate chips using a rubber spatula or wooden spoon. Ensure they are evenly distributed throughout the dough.
7. Chill the Dough (Highly Recommended): Cover the bowl with plastic wrap and refrigerate the cookie dough for at least 1 hour, or preferably for 2-4 hours, or even overnight. Chilling the dough solidifies the fat, preventing the cookies from spreading too much during baking. It also allows the flavors to meld and deepen, resulting in a more flavorful cookie. For truly thick and chewy cookies, don’t skip this step!

Part 2: Baking the Cookies

1. Preheat Oven: About 20 minutes before you’re ready to bake, preheat your oven to 375°F (190°C). Position an oven rack in the center of the oven for even baking.
2. Portion the Dough: Once chilled, remove the cookie dough from the refrigerator. For large cookies suitable for ice cream sandwiches, use a large cookie scoop (about 3 tablespoons or 1/4 cup measure) to portion out mounds of dough. Alternatively, you can roll the dough into balls of approximately 2 inches in diameter. Place them about 3 inches apart on the prepared baking sheets to allow for spreading.
3. Optional – Flatten Slightly: For flatter cookies that are easier to make sandwiches with, you can gently press down on the tops of the dough balls with the palm of your hand or the bottom of a glass before baking.
4. Bake: Bake for 12-15 minutes, or until the edges are golden brown and set, and the centers are still slightly soft. Ovens vary, so keep an eye on them. For chewier cookies, err on the side of slightly underbaking.
5. Cool Cookies: Let the cookies cool on the baking sheets for 5-10 minutes. They will continue to cook slightly from the residual heat. This also allows them to firm up enough to be transferred without breaking. Then, carefully transfer the cookies to a wire rack to cool completely. It’s crucial that the cookies are completely cool before you attempt to add ice cream, otherwise, you’ll have a melty mess. This might take at least 1-2 hours at room temperature.

Part 3: Preparing the Ice Cream and Assembling the Sandwiches

1. Soften Ice Cream (Slightly): About 10-15 minutes before you plan to assemble the sandwiches, take your ice cream out of the freezer and let it sit at room temperature. You want it to be soft enough to scoop and spread easily, but not melted.
2. Match Cookie Pairs: While the ice cream is softening, pair up your cooled cookies by size and shape. You’ll want two similarly sized cookies for each sandwich. Lay one cookie from each pair flat side up on a clean baking sheet lined with parchment paper. This will be the base.
3. Scoop Ice Cream: Once the ice cream is slightly softened, use an ice cream scoop (a standard round scoop works well) to place a generous scoop of ice cream onto the flat side of one cookie in each pair (the ones you laid out). For a neater look, you can also use a method where you slice a cylindrical carton of ice cream into discs, but scooping is generally easier for home use.

   • Alternative Method for Uniformity: If you want very neat, uniform ice cream layers, you can spread the slightly softened ice cream into a parchment-lined 9×13 inch baking pan to a thickness of about 1-1.5 inches. Freeze until solid (2-3 hours). Then, use a round cookie cutter (similar in size to your cookies) to cut out perfect discs of ice cream. This method requires more planning but gives professional results.

4. Top with Second Cookie: Gently place the second cookie of each pair, flat side down, on top of the ice cream. Press down lightly to spread the ice cream to the edges of the cookies, creating a sandwich. Work quickly to prevent the ice cream from melting too much.
5. Optional – Roll the Edges: If desired, immediately roll the exposed ice cream edges of each sandwich in your choice of toppings: mini chocolate chips, sprinkles, chopped nuts, or toasted coconut. This adds an extra layer of flavor, texture, and visual appeal.

Part 4: Freezing for Ultimate Firmness

1. Wrap and Freeze: Individually wrap each cookie ice cream sandwich tightly in plastic wrap or aluminum foil. Alternatively, place them in a single layer in an airtight, freezer-safe container, using parchment paper between layers if stacking.
2. Freeze Until Firm: Place the wrapped sandwiches back into the freezer and freeze for at least 2-4 hours, or preferably overnight, until the ice cream is completely firm and the sandwiches are solid. This step is crucial for preventing them from being too soft or messy to eat. A well-frozen sandwich is a joy to bite into.