Key Lime Pie Recipe

Preheat and prepare pan

Preheat oven to 350°F (175°C). Lightly grease a 9-inch (23 cm) pie dish or use a removable-bottom tart pan.

Make crumb mixture

Combine 1.5 cups graham cracker crumbs, 2 tablespoons granulated sugar, and 1/4 teaspoon fine salt in a bowl. Stir to combine evenly. Pour in 6 tablespoons melted unsalted butter and mix until crumbs are evenly moistened and hold together when pressed.

Form and bake crust

Press the crumb mixture firmly and evenly into the bottom and up the sides of the prepared 9-inch pie dish, using the bottom of a measuring cup for an even layer. Bake in the preheated oven for 8–10 minutes until set and fragrant. Remove from oven and let cool while you prepare the filling. Reduce oven temperature to 325°F (160°C) if you plan to bake the filled pie (see filling step).

Temper and mix yolks (optional step for extra safety)

If you prefer gently cooked custard rather than a completely no-bake filling, whisk the 4 large egg yolks with 1/4 teaspoon cream of tartar in a heatproof bowl. Slowly whisk in 1/2 cup of the key lime juice to temper, then transfer to a small saucepan and cook over low heat, stirring constantly, just until it thickens slightly (do not let it scramble). Remove from heat and let cool slightly before combining with the condensed milk. If you prefer a no-cook traditional Key lime pie, skip cooking and proceed to the next step using egg yolks at room temperature.

Combine filling ingredients

In a medium bowl, whisk together 1 cup sweetened condensed milk, the remaining key lime juice (totaling about 3/4 cup), the 4 egg yolks (tempered or raw if using a trusted pasteurized egg), and 1 tablespoon finely grated lime zest until fully combined and smooth. The mixture will thicken slightly as the acids in the juice gently set the condensed milk and yolks.

Fill crust and bake (or chill)

Pour the filling into the cooled graham cracker crust and smooth the top. For a slightly firmer, cooked set, bake at 325°F (160°C) for 12–15 minutes until the center is just set (it will still have a slight jiggle). Remove and cool to room temperature, then refrigerate for at least 3 hours (preferably overnight) to fully set. For a no-bake version, skip the oven and chill the filled pie in the refrigerator for at least 4 hours.

Whip cream

Chill a mixing bowl and beaters for best results. Pour 1 cup cold heavy cream into the bowl, add 2 tablespoons powdered sugar and 1/2 teaspoon vanilla extract. Whip on medium-high speed until soft to medium peaks form. Do not overbeat.

Top pie

Spread whipped cream over the chilled pie or pipe decorative rosettes around the edge. Return to refrigerator for 15–30 minutes to set before serving.

Before serving, garnish the pie with additional grated lime zest or thin lime slices. Slice with a warm, clean knife for neat slices. Store leftover pie covered in the refrigerator for up to 3–4 days.