Mama's Lemon Cheese Pie

8 oz cream cheese
2 c milk
3 oz instant lemon pudding
1/2 t lemon zest
1/2 t lemon juice
1 graham crust
Cool Whip

Beat cream cheese, then add 1/2 c milk without stirring. Sprinkle on the dry pudding, again without stirring. Gradually add milk, zest, and juice. Beat thick and pour in crust. Freeze. Cut and top each serving with Cool Whip.