In a medium saucepan, combine fresh or frozen blueberries, granulated sugar, cornstarch, and lemon juice. Cook over medium-high heat until boiling, then simmer for 4-8 minutes until thickened. Let cool.

In a mixing bowl, beat softened cream cheese and powdered sugar together until smooth. Fold in whipped topping and chill.

Assemble in an 8x8 inch pan; dip ladyfinger cookies in milk and layer half in the base. Spread half of the blueberry filling and half of the cheesecake filling.

Add another layer of soaked ladyfinger cookies, followed by remaining blueberry filling, and top with remaining cheesecake mixture.

Spread whipped topping over final layer and sprinkle optional white chocolate chips. Cover and refrigerate for at least 6 hours.

Slice into squares to serve, optionally garnishing with fresh blueberries or whipped cream.