Begin by preheating your oven to 350°F. Lightly grease a 7×11 baking dish with cooking spray and set it aside.

In a large microwave-safe bowl, melt the butter and chocolate chips together. Start by microwaving for 30 seconds, then stir. If needed, microwave in 15-second bursts, stirring between each interval, until the mixture is smooth and completely melted. Stir in the cocoa powder until thoroughly blended.

Next, incorporate both the granulated and brown sugars into the mixture, stirring until fully combined. Add the eggs and the extra egg yolk, one at a time, mixing well after each addition. Stir in the vanilla extract and salt, ensuring the mixture is smooth.

Gradually fold in the flour until the brownie batter is well mixed. Set aside ¼ cup of this batter for later use. Spread the remaining brownie mixture evenly across the prepared baking pan.

Now, prepare the cheesecake swirl. In a medium-sized bowl, use an electric mixer to beat the softened cream cheese with the sugar until smooth and creamy. Add the egg and vanilla extract, mixing until the cheesecake layer is fully combined and silky.

Pour the cheesecake mixture evenly over the brownie batter in the pan. Take the reserved ¼ cup of brownie batter and either drop spoonfuls or drizzle it over the cheesecake layer. Use a knife to gently swirl the brownie and cheesecake layers together, creating a marbled effect.

Bake the brownies in your preheated oven for 25-30 minutes. You’ll know they’re done when the center is set, and a toothpick inserted comes out mostly clean, with just a few fudgy crumbs attached.

Let the brownies cool completely before slicing and serving.