Preheat the oven to 350 F (177 C). Line a 9 x 9 (23 cm) pan with parchment paper along the bottom and two sides. Set aside for now.
In a microwave safe mixing bowl add the butter and 1 cup (170 g) of chocolate chips. Heat in 30 second increments, stirring after each until the butter and chocolate are fully melted and mixed together. Whisk in the espresso powder and set aside for a moment.
1 cup (226 g) unsalted butter, sliced, 1½ cups (255 g) semi sweet chocolate chips, divided , 1 tablespoon espresso powder
In another mixing bowl whisk the eggs, sugar, light brown sugar, vanilla extract and salt until smooth and well combined. Whisk in the melted chocolate and butter mixture until smooth and well combined. Whisk in the cocoa powder and flour until smooth and glossy.Before adding in the reserved chocolate chips, scoop out ½ cup of brownie batter into another mixing bowl. This is for the brownie swirl in the cheesecake layer. Fold in the reserved ½ cup (85 g) chocolate chips. 3 large eggs, room temperature, 1 cup (200 g) granulated sugar, ½ cup (100 g) light brown sugar , 2 teaspoons (10 ml) vanilla extract , ½ teaspoon salt, ½ cup (40 g) Dutch processed cocoa powder, ¾ cup (90 g) all purpose flour
Evenly pour the brownie batter into the prepared pan. Par-bake the brownie layer for 15 minutes or until the brownies are just beginning to set. While the brownie layer bakes, prepare the cheesecake layer and the brownie batter for the swirl.
Add 1 tablespoon (15 ml) of hot water to the reserved ½ cup brownie batter. Mix well to combine. The batter should be thinned out enough to swirl easily, but not too thin that it becomes too runny.
1 - 2 tablespoons (15 - 30 ml) hot water
In a large mixing bowl of stand mixer fitted with paddle attachment add the cream cheese and sugar. Cream the the cream cheese and sugar on medium speed for 1 - 2 minutes or until the mixture is smooth and well combined. On low cream in the eggs, sour cream and vanilla extract until smooth and well combined. Set aside for a moment.
16 oz. (453 g) cream cheese, room temperature, ½ cup (100 g) granulated sugar, ¼ cup (60 g) sour cream, room temperature, 2 large eggs, room temperature, 1 tablespoon (15 ml) vanilla extract
Remove the parbaked brownies from the oven. Evenly top the brownie layer with the cheesecake layer. Drop 12 - 14 dollops of reserved and thinned out brownie batter onto the cheesecake layer. Swirl the dollops of brownie batter into the cheesecake layer. Be careful not to overswirl.
Return the cheesecake topped brownies to the oven to finish baking. Bake the cheesecake brownies for another 25 - 35 minutes. Signs this cheesecake brownie is finished baking are a set, puffed up edges that have slightly pulled away from the edge of the pan and are lightly golden. The center of the cheesecake layer should jiggle slightly.
Remove the cream cheese brownies from the oven to cool at room temperature for 1 hour. Cover and transfer the brownies to the fridge to chill and fully set for 3 - 4 hours in the fridge. When it’s time to serve, use the parchment overhang to remove the brownies from the pan, slice and enjoy.