Preheat the oven to 350°F and line a 9×13-inch pan with foil, then lightly grease it.
In a large microwave-safe bowl, melt the butter and chocolate chips in 30-second intervals, stirring until smooth.
Stir in the cocoa powder until fully combined.
Add the granulated sugar, brown sugar, vanilla, and salt, mixing until smooth.
Add the eggs one at a time, mixing well after each addition.
Gently stir in the flour until just combined and no dry streaks remain.
Spread about two-thirds of the brownie batter evenly into the prepared pan.
In a separate bowl, beat the cream cheese and hot fudge together until smooth and creamy.
Spoon the cheesecake mixture evenly over the brownie layer, then gently spread it out.
Drop spoonfuls of the remaining brownie batter over the cheesecake layer and carefully spread to cover.
Sprinkle the top with mini chocolate chips or chopped chocolate.
Bake for 30–38 minutes, until the edges are set and the center still has a slight jiggle.
Let the brownies cool completely at room temperature.
Refrigerate for at least 2 hours before slicing for clean layers.
Cut into squares and serve chilled or slightly softened.