1 can sweetened condensed milk
1 tsp. grated lemon rind
1/2 c. lemon juice
3 1/2 c. thawed Cool Whip
1 graham cracker crust

Combine milk, lemon rind and juice in large bowl. Fold in whipped topping, blending well. Spoon into crust and chill 2 to 3 hours. Garnish with additional whipped topping and lemon slices, if desired.