Line a 20cm springform round cake pan with baking paper.
Combine the base ingredients - the crushed biscuits and the melted butter in a large bowl and press into the prepared pan. Refrigerate while making filling.
Cheesecake Filling
Dissolve the gelatine in the boiling water and set aside to cool until needed.
Using an electric mixer or a stand mixer, beat the cream cheese and the sugar until smooth.
Fold in the gelatin mixture, lemon juice and cream.
Fold through the rosella jam.
Pour the filling into the prepared crust and refrigerate while making the jelly topping.
Jelly Topping
Dissolve the gelatine in the boiling water and set aside to cool until needed.
In a small saucepan, gently heat the rosella syrup, sugar and water over low heat.
When the sugar is dissolved, add the gelatin mixture until combined.
Remove from heat and allow to cool, but not set.
When cool, gently pour over the top of the cheesecake.
Place the cheesecake back in the fridge for at least 4 hours to set completely.