Key Lime Pie is a classic American dessert with a crisp graham cracker crust and a smooth, creamy lime filling. Sweetened condensed milk balances the tart citrus juice, while egg yolks give the filling a rich custard texture without making it heavy.
This version uses a simple baked filling that sets into clean, creamy slices after chilling. It is easy to prepare ahead, making it a practical dessert for warm-weather gatherings, potlucks, and family dinners.
Why This Recipe Works
- Sweetened condensed milk creates a creamy filling: Its concentrated sweetness and low water content help produce a thick, smooth custard.
- Lime juice provides the essential acidity: The tart juice balances the sweetness and gives the pie its bright citrus flavor.
- Egg yolks add richness and structure: They help the filling set during baking while keeping the texture silky.
- A graham cracker crust adds contrast: The crisp, buttery crust complements the soft filling and adds a lightly toasted flavor.
- Chilling finishes the texture: Refrigeration firms the custard and makes the pie easier to slice cleanly.
Equipment Needed
- 9-inch (23 cm) pie plate
- Food processor or resealable bag and rolling pin
- Mixing bowls
- Whisk
- Fine grater or microplane
- Citrus juicer
- Baking sheet
- Wire cooling rack
Ingredients List
Graham Cracker Crust
- 1 3/4 cups finely crushed graham crackers (175 g), about 12 full graham cracker sheets
- 1/4 cup granulated sugar (50 g)
- 6 tablespoons unsalted butter (85 g), melted and cooled slightly
- 1/8 teaspoon kosher salt (0.75 g)
Key Lime Filling
- 4 large egg yolks (72 g), room temperature
- 2 cans sweetened condensed milk, 14 ounces each (794 g total)
- 3/4 cup Key lime juice (180 ml), preferably fresh
- 1 tablespoon finely grated Key lime zest (6 g)
- 1/2 teaspoon vanilla extract (2.5 ml)
- 1/8 teaspoon kosher salt (0.75 g)
Optional Topping
- 1 cup heavy whipping cream (240 ml), cold, for serving
- 2 tablespoons powdered sugar (15 g), for serving
- 1/2 teaspoon vanilla extract (2.5 ml), for serving
- Thin lime slices or extra lime zest, optional, for garnish
Ingredient Notes and Substitutions
- Key lime juice: Key limes provide the traditional floral, tart flavor associated with this pie. If fresh Key limes are unavailable, bottled Key lime juice is a practical substitute. Regular Persian lime juice can also be used, although the flavor will be slightly sharper and less floral.
- Sweetened condensed milk: This ingredient provides sweetness, richness, and much of the filling's characteristic texture. Evaporated milk is not a direct substitute because it contains much less sugar and has a different consistency.
- Egg yolks: Egg yolks give the filling structure and richness. They are essential to the baked custard, so there is no simple direct egg-free substitution for this formula.
- Graham crackers: Graham crackers create the classic crisp, lightly sweet crust. Digestive biscuits can replace them, although they have a slightly different flavor and may require a small adjustment in sweetness.
- Heavy whipping cream: Whipped cream is optional and adds a light, creamy contrast to the tart filling. It can simply be omitted for a more traditional, intensely lime-forward slice.
Step-by-Step Instructions
Step 1: Prepare the oven and pie plate.
Preheat the oven to 350°F (175°C). Place the 9-inch (23 cm) pie plate on a baking sheet to make it easier to transfer in and out of the oven.
Step 2: Make the graham cracker crumbs.
Crush the graham crackers into fine, even crumbs. If using a food processor, pulse until no large pieces remain. If using a resealable bag, crush them with a rolling pin.
Step 3: Mix the crust.
Combine the graham cracker crumbs, granulated sugar, and kosher salt. Pour in the melted butter and stir until all the crumbs are evenly moistened. The mixture should resemble damp sand and hold together when pressed.
Step 4: Form and bake the crust.
Press the crumb mixture firmly into the bottom and slightly up the sides of the pie plate. Use the flat bottom of a glass or measuring cup to compact it evenly. Bake at 350°F (175°C) for 8 to 10 minutes, until lightly golden and fragrant.
Step 5: Cool the crust slightly.
Remove the crust from the oven and let it cool for about 10 minutes while preparing the filling. Keep the oven at 350°F (175°C).
Step 6: Prepare the lime filling.
In a large bowl, whisk the egg yolks until smooth. Add the sweetened condensed milk, Key lime juice, lime zest, vanilla, and kosher salt. Whisk gently until the mixture is completely combined and smooth. Avoid whipping in excessive air.
Step 7: Fill the crust.
Pour the lime mixture into the slightly cooled graham cracker crust. Gently tap the pie plate once on the counter if you see large bubbles on the surface.
Step 8: Bake the pie.
Bake at 350°F (175°C) for about 15 to 20 minutes. The edges should look set while the center should still have a slight jiggle when the pie is gently moved. The filling should reach at least 160°F (71°C) in the center for food safety.
Step 9: Cool completely.
Remove the pie from the oven and place it on a wire rack. Let it cool at room temperature for about 1 hour. The filling will continue to firm as it cools.
Step 10: Chill until firm.
Cover the cooled pie and refrigerate for at least 3 hours, preferably 4 hours or overnight. The center should feel firm when gently pressed.
Step 11: Prepare the optional whipped cream.
Just before serving, beat the cold heavy cream, powdered sugar, and vanilla until medium-stiff peaks form. The cream should hold its shape but remain smooth.
Step 12: Slice and serve.
Cut the chilled pie into 8 slices using a sharp knife. Wipe the knife clean between cuts for neater slices. Top each serving with optional whipped cream and lime zest or a thin lime slice.
Storage, Freezing, and Make-Ahead Instructions
- Store Key Lime Pie covered in the refrigerator for up to 4 days. Keep it refrigerated until serving because the filling contains eggs and dairy.
- For the best texture, add whipped cream shortly before serving rather than storing the pie with the topping for several days.
- The pie can be made 1 day ahead and refrigerated overnight. This longer chilling time makes the filling especially firm and easy to slice.
- To freeze, cool and chill the pie completely, then wrap it tightly in plastic wrap followed by aluminum foil. Freeze for up to 1 month. Thaw overnight in the refrigerator before serving. Add whipped cream and other garnishes after thawing.
FAQ
Can I use regular lime juice instead of Key lime juice?
Yes. Regular Persian lime juice works when Key limes are unavailable, but the flavor will be somewhat sharper and less floral. Use the same 3/4 cup (180 ml) quantity.
Can I use bottled Key lime juice?
Yes. Bottled Key lime juice is a convenient substitute when fresh Key limes are difficult to find. Fresh zest still adds a brighter citrus aroma if available.
Why is my Key Lime Pie runny?
The filling may have been underbaked or not chilled long enough. Bake until the edges are set and the center has only a slight jiggle, then refrigerate for at least 3 to 4 hours before slicing.
Does Key Lime Pie need to be refrigerated?
Yes. Store the finished pie in the refrigerator because the filling contains eggs and dairy. Keep it chilled until ready to serve.
Can I make Key Lime Pie ahead of time?
Yes. The pie can be made a day ahead and refrigerated overnight. For the freshest presentation, add whipped cream and other toppings shortly before serving.
Key Lime Pie
Ingredients
Ingredients
- 1 3/4 cups finely crushed graham crackers (175 g) about 12 full graham cracker sheets
- 1/4 cup granulated sugar (50 g)
- 6 tablespoons unsalted butter (85 g) melted and cooled slightly
- 1/8 teaspoon kosher salt (0.75 g)
- 4 large egg yolks (72 g) room temperature
- 2 cans sweetened condensed milk 14 ounces each (794 g total)
- 3/4 cup Key lime juice (180 ml) preferably fresh
- 1 tablespoon finely grated Key lime zest (6 g)
- 1/2 teaspoon vanilla extract (2.5 ml)
- 1 cup heavy whipping cream (240 ml) cold, for serving
- 2 tablespoons powdered sugar (15 g) for serving
- 1/2 teaspoon vanilla extract (2.5 ml) for serving
- Thin lime slices or extra lime zest optional, for garnish
Instructions
Method
- Prepare the oven and pie plate: Preheat the oven to 350°F (175°C). Place the 9-inch (23 cm) pie plate on a baking sheet to make it easier to transfer in and out of the oven.
- Make the graham cracker crumbs: Crush the graham crackers into fine, even crumbs. If using a food processor, pulse until no large pieces remain. If using a resealable bag, crush them with a rolling pin.
- Mix the crust: Combine the graham cracker crumbs, granulated sugar, and kosher salt. Pour in the melted butter and stir until all the crumbs are evenly moistened. The mixture should resemble damp sand and hold together when pressed.
- Form and bake the crust: Press the crumb mixture firmly into the bottom and slightly up the sides of the pie plate. Use the flat bottom of a glass or measuring cup to compact it evenly. Bake at 350°F (175°C) for 8 to 10 minutes, until lightly golden and fragrant.
- Cool the crust slightly: Remove the crust from the oven and let it cool for about 10 minutes while preparing the filling. Keep the oven at 350°F (175°C).
- Prepare the lime filling: In a large bowl, whisk the egg yolks until smooth. Add the sweetened condensed milk, Key lime juice, lime zest, vanilla, and kosher salt. Whisk gently until the mixture is completely combined and smooth. Avoid whipping in excessive air.
- Fill the crust: Pour the lime mixture into the slightly cooled graham cracker crust. Gently tap the pie plate once on the counter if you see large bubbles on the surface.
- Bake the pie: Bake at 350°F (175°C) for about 15 to 20 minutes. The edges should look set while the center should still have a slight jiggle when the pie is gently moved. The filling should reach at least 160°F (71°C) in the center for food safety.
- Cool completely: Remove the pie from the oven and place it on a wire rack. Let it cool at room temperature for about 1 hour. The filling will continue to firm as it cools.
- Chill until firm: Cover the cooled pie and refrigerate for at least 3 hours, preferably 4 hours or overnight. The center should feel firm when gently pressed.
- Prepare the optional whipped cream: Just before serving, beat the cold heavy cream, powdered sugar, and vanilla until medium-stiff peaks form. The cream should hold its shape but remain smooth.
- Slice and serve: Cut the chilled pie into 8 slices using a sharp knife. Wipe the knife clean between cuts for neater slices. Top each serving with optional whipped cream and lime zest or a thin lime slice.
- Chef: Use room-temperature egg yolks for a smoother filling.
- Chill the pie thoroughly for the best texture before slicing.
