Preheat oven to 180°C (not fan bake). Line the bottom and sides of a 20cm spring-form cake tin with baking paper. Use soft butter or spray oil to help the paper stick. Remove cream cheese from the fridge to come to room temperature.
To melt butter, add to a small heatproof bowl and microwave in 30 second bursts, until melted. Alternatively, add butter to a small pot and heat on low, until melted. Place cheesecake base mix in a large bowl and combine with melted butter. Press into the base and 2cm up the sides. Use a spoon or the bottom of a glass or measuring cup to do this. Bake for about 15 minutes. If the sides have sunk a little after baking, quickly press again with a spoon to create an edge. Place in the freezer to chill.
In a large bowl or bowl of your stand mixer, whip together room temperature cream cheese, cream, sugar and vanilla for about 1 minute, until stiff peaks form.
Dollop filling onto chilled base and spread out evenly. Return to freezer for 1 hour to set.
Pour passionfruit sauce over cheesecake. Slice the cheesecake with a sharp knife, wiping between each cut to create a clean slice.