First, crush the digestive biscuits until they are fine crumbs. Mix them with melted butter and press into the base of a springform pan evenly. Chill it in the fridge for 10 minutes to set before adding the filling.
In a large bowl, beat softened cream cheese with sugar until smooth. Gently fold in whipped cream, vanilla extract, and lemon juice. Pour this mixture over the chilled biscuit base and smooth the top with a spatula.
Warm blueberry jam in a small saucepan and stir in fresh blueberries. Let it cool slightly before spooning it over the cheesecake. Spread evenly to create a glossy, fruit-filled topping.
Refrigerate the cheesecake for at least 4 hours, or overnight if you can wait. This helps the filling firm up and allows the flavors to meld beautifully.