Pre-heat your oven to 180℃ Fan/370℉. Line an 8" Square Pan with greaseproof paper.
In a large mixing bowl, whisk together melted butter and both sugars. Add in the eggs, vanilla, vinegar, and food color and mix again. It should look a really bright red, feel free to add more if using liquid/less if using gel.
Add the flour, chocolate chips and cocoa powder, fold gently into the wet mixture with a rubber spatula or wooden spoon until just combined. Pour into the lined tin.
Make the cheesecake layer by whisking the ingredients together until smooth - you may want to use an electric mixer for the cream cheese to really get the lumps out. Pour over the brownie batter and swirl using a knife.
Bake 30 minutes (up to 35 minutes) - until the center is only a little wobbly. Remove and let cool completely before slicing and serving.