1-First Step: Prepare and measure Preheat the oven to 350°F (175°C). Grease a 9-12 inch round cake pan, pizza pan, or springform pan, or line the pan with parchment paper for easy removal. Gather all ingredients and set butter and eggs at room temperature so they mix smoothly. Measure ingredients precisely: this helps the dough hold together and bake evenly.

2-Second Step: Mix dry ingredients In a medium bowl, whisk together the dry ingredients: 2.5 cups all-purpose flour, 1 teaspoon baking soda, and 1 teaspoon salt. Whisking distributes the leavening and salt uniformly so the cake bakes evenly.

3-Third Step: Cream wet ingredients In a large bowl using a hand mixer or stand mixer, cream 1 cup softened butter with 1 cup brown sugar and 1/2 cup granulated sugar until light and fluffy, about 2 to 3 minutes. Add 2 eggs one at a time, mixing after each addition, then add 2 teaspoons vanilla extract. Scrape the bowl to keep the mixture uniform.

4-Fourth Step: Combine wet and dry Gently add the dry ingredients to the wet mixture in two additions. Mix on low speed or fold with a spatula until just combined. Avoid overmixing; overworking the dough will make the final cake tough rather than tender and chewy.

5-Fifth Step: Add mix-ins and shape Fold in 2 cups chocolate chips (or your chosen mix-ins) until evenly distributed. Press the dough evenly into the prepared round pan. Use an offset spatula or the back of a spoon to smooth the top so it bakes uniformly. If you prefer a slightly thicker cake, use a 9-inch pan; for thinner, use 12-inch.

6-Sixth Step: Bake and monitor Bake at 350°F for about 15 to 25 minutes depending on pan size and oven. For a 10-inch pan, check at 18 to 22 minutes. The cookie cake should be golden brown on top with a slightly soft center; it continues to set as it cools. Avoid overbaking to preserve chewiness.

7-Seventh Step: Cool completely before decorating Allow the cookie cake to cool fully in the pan on a rack. Cooling time is important: frosting will melt on a warm cake and decorations will slide. For best results, cool 45 minutes to 1 hour or chill briefly to speed the process. Use this time to prepare the frosting.

8-Final Step: Frosting, decorating, and serving Make a cream cheese frosting by beating 8 ounces cream cheese with 1/4 cup butter until smooth. Gradually beat in 2 cups powdered sugar and 1 teaspoon vanilla extract until thick and spreadable. Spread the frosting evenly across the cooled cookie cake. Add occasion-themed decorations such as colored sprinkles, writing icing, candy letters, or themed toppers for birthdays, holidays, or events. Serve in wedges like a pie so every guest gets a shareable portion.