Preheat oven to 325 degrees. In medium bowl, beat egg yolks; stir in sweetened condensed milk. ReaLemon brand and food coloring, if desired. Pour into prepared pie shell. Bake 30 minutes. Cool. Chill. Spread with whipped cream or topping. Garnish as desired. Refrigerate leftovers.
Key Lime Pie: Substitute 1/2 cup ReaLime juice for lemon.