Vanilla cheesecake filling:

• Add the cream cheese, sugar, heavy cream, egg and vanilla to a bowl. Whisk on medium-low speed until a creamy mixture forms, scraping the bowl as you go. Do not overmix. Set aside

Chocolate cheesecake filling:

• Add the chocolate and heavy cream to a microwave safe bowl. Microwave in 20 second increments until the chocolate melts into the cream to form a smooth ganache. Avoid overheating or overmixing
• Separately, whisk the cream cheese with the sugar on medium-low speed until a creamy mixture forms
• Fold the ganache into the cream cheese mixture gently until combined, scraping the bowl as you go. Do not overmix. Set aside

Red velvet brownie batter:

• Add the butter to a saucepan. Cook and stir on medium heat for a few minutes until the butter has melted and you see brown specks in it. It will also smell nutty at this point. Remove from heat quickly once the butter reaches this stage to avoid getting it burned
• Add the dark chocolate to the butter and stir to melt it in
• In a large bowl, whisk the white sugar, brown sugar, eggs, and vanilla on high speed until a very pale, frothy and light mixture forms (at least 3-4 minutes)
• Whisk in the vinegar, red food color and butter/chocolate mixture until combined
• Sift in the flour, cocoa powder and salt, and use a rubber spatula to very gently fold until just combined. Do not overmix
• You can fold in the chopped chocolate here, or add it during assembly. I recommend the later as the brownie batter is easier to spread without the chocolate in it

Assembly and baking:

• Pre-heat your oven to 350F (conventional / no fan) and line a 9x9" baking pan with parchment paper
• You can layer the brownie batter and two cheesecake fillings however you like (e.g., add the brownie layer, then top one by one by each cheesecake filling, or add the brownie layer and then dollop on and swirl the two cheesecake fillings) -- see notes
• To follow my method exactly (see pictures in blog post above), first spread half of the brownie batter and top with some chopped chocolate. Then pipe the two cheesecake fillings in thick alternating lines. Top off with the remaining brownie batter, and dollop on any remaining cheesecake fillings. Use a toothpick to swirl the cheesecake fillings, and decorate with chopped chocolate -- see notes
• Once assembled, bake in the pre-heated oven for 30-35 minutes until a toothpick inserted in the middle comes out with moist, sticky crumbs attached
• Let the brownies rest in the pan for at least 20 minutes at room temperature. Then transfer to the fridge for 1 hour to fully set them before slicing and eating

Video tutorial: