In a saucepan add blueberries,granulated sugar,lemon juice and 1 tbsp water.Bring this to a boil over medium low heat.Boil for about 3 to 4 minutes while stirring.
Mix cornflour in 2 tbsp water and add to the blueberry mix.Gently stir the mixture and cook until it thickens.Once the sauce turns thick,switch off the flame and allow to cool completely.
Next,to prepare the biscuit base,crush the biscuits in a blender/food processor to form a fine crumb.In a bowl,stir together the biscuit crumbs and the melted butter until well combined.Press the mixture into the bottom of the springform pan or individual serving bowls.Refrigerate until required.
In a large bowl combine together ,cream cheese,heavy cream,powdered sugar and vanilla.Beat with a whisk or a mixer until stiff peaks form.
Pour this cream cheese mixture over the base and spread until even.Refrigerate for atleast 2 hours.Top with the blueberry filling and serve.(You could also swirl the bluberry sauce into the cream cheese layer using a fork or a skewer if desired.)