Peanut Butter Pie

3 oz cream cheese
1 c powdered sugar
1/3 c peanut butter
1/4 c milk
1 pkg (9 oz) Cool Whip
8 inch Graham cracker crust

Whip cream cheese until soft and fluffy. Beat in powdered sugar and peanut butter. Slowly add milk, blending thoroughly into mixture. Fold Cool Whip into peanut butter mixture. Pour into graham cracker crust. Chill until firm.