Gently mix the Cream Cheese, Vanilla, and Caster sugar together in a large mixing bowl. Whip the Double cream until thick, then add to the Cream Cheese mixture. Roughly crush half of the Maltesers into the mixture and gently fold everything together. Remove tin from the fridge and spoon mixture onto the Cookie base. Make sure the mixture is pushed into the sides of the tin. Take the remaining Maltesers, crush them, and sprinkle onto the top of the Cheesecake.