Preheat the oven to 350°F. Line an 8-inch square baking pan with parchment paper and lightly coat with nonstick spray; set aside. In a double boiler over low heat, melt the chocolate chips and butter together, stirring until smooth. Remove from the heat, whisk in the cocoa powder, and let the mixture cool for 10 minutes. Whisk in the granulated sugar and brown sugar until fully incorporated. Add the eggs one at a time, whisking thoroughly. Stir in the vanilla extract and salt, then gently fold in the flour until just blended; set aside. In a medium bowl, beat the cream cheese and granulated sugar with a hand mixer until smooth and creamy, about 2 minutes. Add the egg and vanilla extract, beating until the mixture is well combined. Pour the prepared brownie batter into the pan, reserving about ¼ cup of the batter. Spread the cream cheese topping evenly over the brownie layer. Drop the reserved brownie batter over the top and swirl gently with a knife to create a marbled effect. Bake for 30–40 minutes, or until the center is set and a toothpick inserted comes out mostly clean with a few fudgy crumbs. Allow the brownies to cool completely before slicing and serving.