Instructions

• Preheat the oven to 325°F. Spray a 9x13-inch baking pan with nonstick cooking spray and set aside.
• In a medium bowl, whisk together 2 1/8 cups all-purpose flour, 1/2 teaspoon salt, and 1/2 teaspoon baking soda. Set aside.
• In the bowl of a stand mixer (or a large bowl if using a hand mixer), combine 12 tablespoons melted butter (cooled to room temperature), 1 cup light brown sugar, and 1/2 cup granulated sugar. Mix until combined.
• Add 1 large egg, 1 large egg yolk, and 2 teaspoons vanilla extract to the butter–sugar mixture. Mix until smooth.
• With the mixer on low speed, slowly add the dry ingredients to the wet ingredients. Mix just until combined—do not overmix.
• Stir in 2 cups chocolate chips by hand until evenly distributed.
• Press the cookie dough evenly into the prepared 9x13-inch pan, smoothing the top with a spatula. If desired, sprinkle the top very lightly with sea salt.
• Bake the cookie base for 25–30 minutes, or until the top is light golden brown and the edges start to pull away from the pan. Remove from the oven and let the cookie bars cool completely in the pan.
• While the cookie base cools, let 1.5 quarts of chocolate chip cookie dough ice cream sit at room temperature for about 30 minutes, until softened enough to spread but still slightly frozen.
• When the cookie bars are completely cool, evenly spread the softened ice cream over the cookie base. Sprinkle 1/3 cup chocolate chips over the ice cream.
• Cover the pan (wrap with plastic wrap or use a lid) and freeze until the ice cream is fully hardened, at least 2 hours.
• To serve, remove the pan from the freezer. Heat a sharp knife by running it under very hot water, dry the blade, and cut the frozen bars into squares. Reheat and dry the knife between cuts for cleaner slices. Drizzle with hot fudge sauce, if desired, and serve.