In a large mixing bowl combine softened cream cheese and sweetened condensed milk with an electric hand mixer until there are no lumps (The better quality cream cheese the easier it is to have no lumps). Takes about 3 minutes on medium speed.
Fold in vanilla and lemon juice gently with a spoon. The mixture will be thin and then, thicken up quickly from lemon juice.
Scoop mixture into graham cracker crust. Spread evenly.
Place in fridge for at least 4 hours; over night is best.
Carefully, spread chilled pie filling over cream cheese mixture, cut, and enjoy.