Key Lime Pie

1 8oz pkg. cream cheese
1 can sweetened condensed milk
1 T. vanilla
½ c. fresh key lime juice (I've used this or just the lime juice from the store, and they're both pretty similar)
1 graham cracker crust (I buy them pre-made)
2 c. cool whip

Blend cream cheese with a mixer until smooth. Slowly add sweetened condensed milk beating constantly until all lumps are gone and mixture is smooth. Add vanilla and lime juice, beat until light and fluffy. Pour into crust. Refrigerate overnight (at least 4 hours). Before serving, top with cool whip or whipping cream.