Grease and line a 20x20cm square tin with baking paper and preheat oven to 170°C (fan forced).
Combine raspberries, sugar, cornflour and lemon juice in a medium saucepan, stir and bring to a boil. Reduce heat and simmer for 7-8 minutes stirring often. When thickened, remove from heat and set aside to cool.
In a food processor add cream cheese and sugar, and blend until smooth (about 2 minutes). Add sour cream, egg and vanilla and process for another 30 seconds. Pour the cheesecake mixture over the cooled biscuit base and tap the tin on the bench once or twice to remove any air bubbles.
Dollop large spoonfuls of raspberry topping over the cheesecake and use a skewer to gently swirl topping throughout the surface of the cheesecake.
Bake for 35-40 minutes until the edges are firm and the centre has a slight jiggle. Remove from oven and allow to cool completely at room temperature. Then allow to set in fridge for a minimum of 4 hours or overnight. Slice and enjoy!