1-First Step: Preheat your oven to 350 degrees Fahrenheit. While the oven heats up, prepare a 9×13 inch pan by lining it with parchment paper, making sure to leave some overhang on the sides for easy removal later. Alternatively, you can spray the pan thoroughly with nonstick cooking spray. This preparation ensures your bars won’t stick to the pan and makes cleanup a breeze.

2-Second Step: In a large mixing bowl, cream together the 1 1/2 cups of softened salted butter and the 3/4 cup of granulated sugar. Use an electric mixer on medium speed for about 2-3 minutes until the mixture is fully combined and looks fluffy. This step is crucial for incorporating air into the dough, which helps create a lighter texture in the finished bars.

3-Third Step: Add the 2 eggs and 2 teaspoons of vanilla extract to the butter and sugar mixture. Mix on medium speed until well blended, scraping down the sides of the bowl as needed. The batter should be smooth and uniform in color at this point, with no visible streaks of egg.

4-Fourth Step: In a separate bowl, whisk together the 3 cups of all-purpose flour, 1/2 cup of Dutch processed cocoa powder, 1 cup of powdered sugar, 1 1/2 tablespoons of corn starch, 1 1/2 teaspoons of baking powder, and 3/4 teaspoon of salt. Mixing the dry ingredients separately helps ensure even distribution throughout the dough. Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed at first to prevent flour from flying out of the bowl. Once most of the flour has been incorporated, increase the speed to medium and mix until a soft dough forms. Be careful not to overmix, as this can make your bars tough instead of tender. The dough should be thick and pliable, similar to playdough.

5-Fifth Step: Transfer the dough to your prepared 9×13 inch pan. Using clean hands or the back of a spatula, press the dough evenly into the pan, ensuring it reaches all corners and has a uniform thickness. For the most even results, you can place a piece of parchment paper over the dough and use a rolling pin to roll it smooth. Prick the surface lightly with a fork in a few places to allow steam to escape during baking.

6-Sixth Step: Place the pan in the preheated oven and bake for 18-23 minutes. The bars are done when the top is shiny and slightly flaky, and a toothpick inserted in the center comes out clean or with just a few moist crumbs. Avoid overbaking, as this will make the bars dry instead of soft and chewy.

7-Seventh Step: Remove the pan from the oven and let it cool completely on a wire rack before frosting. This is important because if you try to frost warm bars, the frosting will melt and slide right off. Depending on your kitchen temperature, this could take anywhere from 1-2 hours. For faster cooling, you can place the pan in the refrigerator for about 30 minutes, but don’t rush this step!

8-Eighth Step: While the bars are cooling, prepare the frosting. In a medium bowl, whip together the 1/2 cup of softened salted butter and the 3 ounces of softened cream cheese until smooth and well combined. Using an electric mixer makes this process much easier and ensures a creamy, lump-free frosting.

9-Ninth Step: Gradually add the 2 2/3 cups of powdered sugar to the butter and cream cheese mixture, mixing well after each addition. Start with low speed to prevent a cloud of powdered sugar, then increase to medium and mix until smooth and creamy. This gradual approach helps prevent lumps and ensures a silky texture.

10-Tenth Step: Mix in the 2/3 cup of Dutch processed cocoa powder and vanilla extract (if using additional vanilla) until fully incorporated. The frosting should be thick, creamy, and smooth with a rich chocolate color.

11-Eleventh Step: Check the consistency of your frosting. It should be spreadable but not too thin. If needed, adjust the consistency by adding milk 1 teaspoon at a time, mixing well after each addition, until you reach your desired spreadability.

12-Twelfth Step: Once the bars have cooled completely, spread the frosting evenly over the top using an offset spatula or the back of a spoon. Start from the center and work your way outward for the most even distribution.

13-Thirteenth Step: Sprinkle colored sprinkles over the frosted bars while the frosting is still slightly tacky to help them adhere. This is where you can get creative with colors to match holidays, seasons, or special occasions.

14-Final Step: For the cleanest cuts, chill the bars in the refrigerator for at least 30 minutes before slicing. Use a large, sharp knife and wipe it clean between cuts for perfect edges. Cut into 24 bars and serve at room temperature for the best texture and flavor.