Pre-bake pie shells according to package directions. While they are baking begin your lime curd.
Use a zester or grater to zest 2 limes, careful not to get any of the white pith. Juice enough limes to get 1/2 cup of juice (about 4-6 depending on size).
In a small bowl beat together whole eggs and egg yolks. In a medium saucepan off heat stir together lime juice, lime zest, sugar, beaten eggs, and salt until smooth.
Turn on heat to medium low and cook mixture, stirring constantly until thickened, about 10 minutes. Do not allow to come to a simmer and do not allow to sit or you chance scrambling the eggs.
Curd is thick enough when it coats the spoon and a swipe of your finger leaves a stripe, as pictured. Turn off heat, cover and let cool 20 minutes.
Stir lime curd and spoon into prepared crusts, spreading out to fill evenly. Refrigerate uncovered (this forms a nice skin on top) at least 2-4 hours. Serve chilled.
Add whipped cream if desired: In a chilled bowl of a stand mixer equipped with a wisk attachment add cream, powdered sugar, and vanilla. Wisk on medium speed until stiff peaks form, careful not to over whip so you don't make butter. ;)
