19-inch graham cracker crust(Store bought or make your own)
14ozsweetened condensed milk
2/3cupkey lime juice(You'll need about 1 dozen key limes)
1tbsfinely grated lime zest(Plus more for garnish)
3egg yolks
3/4cupheavy cream, chilled
sugar(1 to 2 tbs, optional)
Instructions
Preheat the oven to 350 F and place the rack in the middle of the oven.
Whisk together condensed milk, key lime juice, lime zest, and egg yolks. Pour into the prepared crust.
Bake for 15 minutes. The center won't be entirely set, that'll happen as it cools. Remove from oven and let cool completely on a wire rack, then transfer to the fridge to chill for at least 2 hours, but up to 8 is best.
Just before serving, combine cream and sugar in a large mixing bowl. Whisk on medium until soft peaks form, about 2 to 3 minutes. Spoon over pie, garnish with zest, and enjoy!
Notes
If you're looking for a stiffer filling, try using the whole egg instead of just the yolks. The protein in the whites will harden in the heat of the oven, lending structure to the filling.