Preheat oven to 350°F (175°C). Grease a 9×13-inch baking pan.
In a medium saucepan, melt butter over low heat. Stir in sugar, eggs, and vanilla until smooth. Whisk in flour, cocoa powder, salt, and baking powder. Mix well.
Pour half of the brownie batter into the prepared pan, spreading evenly. Set aside the remaining batter.
Beat cream cheese and sugar until smooth. Add egg and vanilla extract, mixing until combined.
Spread this cheesecake mixture evenly over the brownie layer.
Gently spread the remaining brownie batter over the cheesecake layer. Don’t worry if it’s uneven; it will spread while baking.
Bake for 30-35 minutes or until a toothpick inserted into the brownie portion comes out with a few moist crumbs. Let cool.
In a saucepan, heat heavy cream until just simmering. Remove from heat and stir in chocolate chips until smooth.
Allow ganache to cool slightly, then pour over cooled brownies and spread evenly.
Refrigerate for at least 1 hour to set ganache. Once set, slice into squares and enjoy!