Note: If Key limes aren't available, use regular fresh lime juice or bottled key lime juice.
2 large eggs
1 (14 ounce) can sweetened condensed milk
1 packet unflavored gelatin
1/2 cup fresh key lime juice
8 ounces softened cream cheese
4 ounces sour cream
1 cup heavy cream, whipped with some sugar
9-inch graham cracker crust
Key lime slices, optional
Beat eggs in a medium bowl with mixer on high for 2 minutes. Beat 2 minutes longer on medium speed while adding milk and gelatin.
Pour mixture into a saucepan and cook on low to simmer, stirring constantly until thickened, about 15 to 20 minutes.
Remove from heat and stir in 1/4 cup lime juice, stirring until smooth and thick. Let cool.
Beat the cream cheese, sour cream and remaining lime juice until smooth. Fold in the whipped cream and then the milk/gelatin mixture mixing well.
Pour into pie crust and refrigerate until set, about 2 1/2 hours or overnight. Garnish with lime slices.