In a bowl, sift together the all-purpose flour, cornstarch and salt and set it aside.
75 g all-purpose flour, 1 tablespoon cornstarch, ½ teaspoon salt
Melt the butter and chocolate together. Once melted, pour it into a large bowl and add the cocoa powder and stir it together with a rubber spatula until smooth.
90 g butter, 75 g semi-sweet dark chocolate chips, 35 g unsweetened Dutch cocoa powder
Add the granulated sugar and dark brown sugar, and mix it together with an electric mixer until combined.
100 g granulated sugar, 150 g dark brown sugar
Then add the eggs and mix for 2 minutes on medium-high speed.
3 large eggs
Add the vegetable oil and vanilla extract and whisk it until combined.
70 g vegetable oil, 1 ½ teaspoon vanilla extract
Finally, add the dry ingredients to the batter and gently mix it together, on low speed, until combined.
Pour most of the brownie batter into the prepared baking pan, leaving about 4-5 teaspoons in the bowl for topping the cheesecake filling with. Smooth out the brownie batter.
Add dollops of the cheesecake filling on top of the brownie batter and smooth it out a bit. Then dollop the remaining brownie batter over the cheesecake batter and with a toothpick or butter knife, swirl the cheesecake and brownie batter together.
Bake for about 50-55 minutes. Once baked, let it cool down for 30 minutes on a wire rack at room temperature, then refrigerate for 1 hour or more and it’s ready to be served.