Preheat oven to 350°F. Line an 8-inch square baking pan with parchment paper and lightly grease with nonstick cooking spray; set aside.
In a double boiler set over low heat, melt chocolate chips and butter, stirring occasionally, until smooth.
1 cup semisweet chocolate chips, ½ cup unsalted butter
Remove the pot from the heat and whisk in the cocoa powder, then set it aside to cool for 10 minutes.
¼ cup unsweetened cocoa powder
Whisk in the sugars and stir until completely combined. Add the eggs and whisk well.
1 cup granulated sugar, ¼ cup brown sugar, 3 large eggs
Stir in the vanilla and salt, then fold in the flour until just combined. Set aside and prepare the cream cheese topping.
1½ teaspoons pure vanilla extract, ½ teaspoon kosher salt, 1 cup all-purpose flour
Place the cream cheese and sugar in a medium bowl, and use a hand mixer to beat until it’s combined and creamy, about 2 minutes.
8 ounces cream cheese, ¼ cup granulated sugar
Add the egg and vanilla extract, beating until well combined.
1 large egg, ½ teaspoon pure vanilla extract
Pour the brownie batter into the prepared pan, reserving about ¼ cup and setting it aside. Pour the cream cheese mixture over the brownie batter. Drop the remaining brownie batter over the cream cheese layer, then use a knife to swirl the layers together.
Bake for 30-40 minutes, or until the center is set and a toothpick inserted comes out mostly clean with only a few fudgy crumbs.
Allow the brownies to cool completely before cutting and serving.