Preheat the oven to 325°F (160°C). Spray an 8" x 8" (20 x 20 cm) square pan with cooking spray and line it with parchment paper, leaving an overhang around the edges.
In a medium bowl, sift together the flour, baking powder, and cocoa powder; set aside.
In a heatproof bowl, add the butter and 230 g chocolate and microwave on 50% power for 30 seconds. Stir well with a silicone spatula. Continue microwaving in 10-15-second bursts, stirring in between each burst. As the chocolate and butter begin to melt, stir gently to prevent lumps. Stop microwaving when only a few small pieces of chocolate and butter remain. The residual heat will melt the rest. Let cool.
In the bowl of a stand mixer with the paddle attachment, add sugar, light brown sugar, vanilla, salt, and eggs. Beat on medium speed until well blended, about 1 minute. Add cooled chocolate mixture and mix until well combined.
Add the flour mixture and the remaining 100 g chocolate chips, mixing until just blended. Do not overmix. Pour batter into the pan in an even layer.
Dollop pumpkin cheesecake filling over the brownie batter. Use a wooden skewer or butter knife to swirl the brownie batter into the cheesecake filling using a figure-8 motion.
Bake for 40 to 50 minutes, until the center is just set when you lightly jiggle the pan. Cool on a wire rack for 1 hour. Refrigerate until cold, about 3 hours. Cut pumpkin cheesecake brownies into squares and serve!