A Key West pie with a creamy, tangy lime filling on a Graham cracker crust, topped with golden meringue.
Key lime makes itself known from the very first bite : bright and tangy, layered over a smooth, cool filling. The Graham cracker crust gives a crisp crack under the fork, while the golden meringue melts on the tongue with a hint of toasted sugar. The pie seems simple enough, but its balance relies on a few precise steps. Here, in the style of Key West’s Aunt Sally, the filling thickens before it even reaches the oven : the baking is mainly there to brown the meringue.
What makes a “ Key ” pie ?
Key lime pie takes its name from the Key lime, the small citrus fruit native to the Florida Keys. In American cuisine, what sets it apart is one essential choice : genuine Key lime juice rather than a generic substitute. It rests on three elements: a Graham cracker crust, a citrus filling, and meringue.
The filling thickens quickly thanks to the combination of egg yolks, sweetened condensed milk, and lime juice : the acidity sets the condensed milk, creating a tangy cream that slices cleanly. The crust adds a sandy crunch, while the meringue brings an airy, lightly caramelized finish, much like other indulgent desserts.
Key West origins and Aunt Sally’s recipe
Key lime pie is deeply tied to the Florida Keys : local lime juice, sweetened condensed milk, a Graham cracker crust, and meringue. The reference recipe is attributed to Aunt Sally of the Curry Mansion Inn in Key West and is often presented as the original version. The formula is simple : four separated eggs, Key lime juice, sweetened condensed milk, a Graham cracker crust, and a meringue baked until golden.
The key point : the filling does not set through prolonged baking. It thickens before it goes into the oven thanks to the reaction between the lime juice and the sweetened condensed milk, which keeps the citrus flavor bright and pronounced. The oven, set to about 180 °C, is used mainly to color the meringue.
The pie’s main ingredients
Key lime juice is the defining element : it brings the characteristic acidity and, with sweetened condensed milk, creates a filling that slices cleanly.
Sweetened condensed milk provides the sweetness, dairy richness, and silky texture that balance the acidity. The egg yolks, whisked until pale and thick before the juice and condensed milk are added, create a smooth, cohesive filling. The Graham cracker crust forms the crumbly base, its mellow sweetness balancing the tartness.
The reserved egg whites become the meringue : whipped with a little cream of tartar, sweetened gradually, spread over the entire pie right to the edges, then browned in the oven.
Hallmarks of authenticity
For that classic “ Key ” character, Aunt Sally’s version relies on real Key lime juice, a filling that sets through acidity rather than prolonged baking, and a meringue finish. The finished pie is chilled before serving so it holds its shape in neat slices, with the golden meringue as its signature touch.
Ingredients
Filling
- 4 eggs separated
- 120 ml Key lime juice
- 1 can sweetened condensed milk 397 g
Crust
- 1 20 cm Graham cracker pie crust
Meringue
- 4 egg whites reserved
- 65 g sugar
- 0.25 teaspoon cream of tartar
Instructions
Filling
- Beat the egg yolks until pale and thick.4 eggs
- Whisk in the Key lime juice, then the sweetened condensed milk, and stir until thickened.120 ml Key lime juice, 1 can sweetened condensed milk
- Pour the filling into the pie crust.1 20 cm Graham cracker pie crust
Meringue
- Whip the egg whites with the cream of tartar until stiff peaks form.4 egg whites, 0.25 teaspoon cream of tartar
- Add the sugar gradually, beating until glossy peaks form.65 g sugar
- Spread the meringue over the entire pie, sealing it to the edges of the crust.
- Bake at 180°C for about 20 minutes, until the meringue is golden brown.
- Chill before serving.
