Add all the cream cheese and mascarpone in a bowl and whip until smooth, approximately 4 minutes.
Toss in the sugar ¼ cup at a time and whip until smooth, approximately 30 seconds. Repeat until all the sugar is whipped and dissolved into the cream cheese.
Add in the vanilla and salt and whip for 1 further minute.
Add 1 egg and beat until well combined and repeat with the remaining egg and egg yolks.
Toss in the cream and whip for a further 4 minutes, until the mixture is smooth and increased in volume.
Either divide the batter into two portions of ⅓ and ⅔’s, whisking half the blueberry jam into the smaller portion or add half the blueberry jam to the cheesecake.
If dividing, alternate pouring each into the cake tin and either leave or swirl in the tin.
Place the cake tin in the center of a deep roasting pan and carefully place in the oven.
Pour boiling water into the roasting pan half way up the outside of the cake tin.
Bake for 1 hour 30 minutes or until lightly golden and only slightly jiggly in the center.
Turn the oven off and leave the oven door slightly ajar for 2 hours.
Remove and place in the fridge for a minimum 4 hours.
When ready to serve, spread the remaining jam on top evenly.
Garnish with whipped cream and fresh blueberries.