Instructions

• Preheat oven to 350°F (177°C). Line a 9-inch round cake pan with foil and spray the foil with nonstick cooking spray.
• In a large bowl (or the bowl of a stand mixer fitted with the paddle), combine ½ cup (113 g) melted unsalted butter, ⅓ cup (67 g) granulated sugar, and ½ cup (100 g) packed brown sugar. Mix on low speed until smooth.
• Add 1 large egg and 1 teaspoon vanilla extract. Mix on medium speed until fully combined, scraping the sides of the bowl as needed.
• Add ½ teaspoon salt and ½ teaspoon baking soda and mix briefly to incorporate.
• Gradually add 1 ½ cups (186 g) all-purpose flour and mix on low just until the dough comes together and is smooth. Scrape the sides of the bowl as needed; do not overmix.
• Slowly mix in 1 ½ cups (275 g) chocolate chips until evenly distributed.
• Press the cookie dough evenly into the prepared 9-inch pan, smoothing the top so the dough reaches the edges.
• Bake for 21–25 minutes, until the top is slightly golden and a toothpick inserted in the center comes out clean or with a few moist crumbs.
• Remove from the oven and let the cookie cake cool in the pan on a wire rack until completely cool before frosting.
• To make the frosting, place 4 tablespoons (57 g) softened unsalted butter in a large bowl and beat until smooth.
• Add 1 cup (113 g) powdered sugar, 2 tablespoons (10 g) unsweetened cocoa powder, and ¼ teaspoon salt. Mix on low until the mixture is combined and somewhat crumbly.
• Mix in ½ teaspoon vanilla, then add 1 tablespoon heavy whipping cream or milk and beat until smooth. Add the remaining 1 tablespoon heavy cream or milk if needed to reach a piping consistency.
• Transfer the frosting to a piping bag fitted with a large star tip and pipe swirls around the edges of the cooled cookie cake (or spread the frosting as desired).
• Store the frosted cookie cake in an airtight container for up to 3 days. Freeze the unfrosted cookie cake for up to 1 month.