Traditional Key Lime Pie

This quick and easy key lime pie recipe starts with a graham cracker crust and is filled with a mixture of egg yolks, sweetened condensed milk, key lime juice & zest. Topped with fresh whipped cream and a lime twist garnish, it's a refreshing pie that tastes like the tropics and is a must-make this summer!

Looking for more key lime recipes? Try my No-Bake Key Lime Cheesecake and Key Lime Pie Bars.

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Over ten years ago, I was on vacation in Florida, having lunch at a fabulous restaurant called the Old Key Lime House, when I faced the all-important decision of what to order for dessert. 

There was a triple-layer chocolate cake which would normally be my go-to. But there was also homemade key lime pie, and since the restaurant bore the iconic dessert’s name, I HAD to order it! 

One bite in, and I was completely smitten with the flavor and cool, creamy texture. I vowed then and there to eat (and make!) more key lime pie. 

The History of Key Lime Pie

Key lime pie dates back to the late 1800s in the Florida Keys. Modern refrigeration wasn't available at the time, so fresh milk wasn't a common commodity. Instead, canned milk was widely used. As a result, this incredibly easy pie came to be.

Believe it or not, up until recently, this was a purely no-bake pie. Combining the lime juice with the egg yolks and condensed milk creates a chemical reaction that causes the mixture to thicken all on its own (the acid causes the proteins in the yolks and milk to bond together).

Nowadays, the pie is baked due to concerns over raw eggs, creating a much better filling consistency since it sets wonderfully and is less droopy than its unbaked counterpart.

Key lime pies can be made with a graham cracker crust (featured here) or pastry pie crust, meringue topping (more traditional), or a whipped cream topping (more modern). 

Ingredients Overview

Only four ingredients each are needed for the graham cracker pie crust and the classic key lime pie recipe; a very simple pie indeed! 

• Graham Cracker Crumbs: You can crush whole graham crackers or buy the boxed graham cracker crumbs.
• Light Brown Sugar: To sweeten the crust.
• Melted Butter: To hold the pie crust together.
• Salt: Balances the flavors of the graham cracker crust.
• Sweetened Condensed Milk: You need one 14-ounce can; this will thicken and sweeten the filling.
• Key Lime Juice: Fresh juice from key limes is preferred, but if you can’t get fresh key limes, then you can use bottled juice; Nellie & Joe’s Key Lime Juice is the best! You can find it at most grocery stores.
• Key Lime Zest: If you cannot find key limes, you can use regular lime zest.
• Egg Yolks: The yolks thicken and add richness to this pie. Use the leftover egg whites for a meringue topping or meringue cookies!

Key Limes vs. Regular Limes

If you’ve never seen key limes, you might wonder what the difference is between the two. 

Key limes are significantly smaller than regular (Persian) limes and are more acidic, resulting in a tarter flavor. Their flesh and juice are also yellow in color, unlike the traditional green color of regular limes.

How to Make Key Lime Pie

After eating it for the first time, I was convinced that authentic key lime pie filling was an elaborate curd/custard that would need to be painstakingly cooked on the stove and then baked in the oven. Not so!

1. Prepare the Filling: Whisk together the lime zest, egg yolks, sweetened condensed milk, and lime juice, then set it aside to thicken.
2. Make the Graham Cracker Crust: Stir together my favorite graham cracker crust, press it into a 9-inch pie pan, and bake it briefly, then let it cool to room temperature.
3. Bake the Pie: Once the crust cools, pour the thickened filling into it and bake until it is mostly set but still jiggles a bit.
4. Chill Out! After the pie cools to room temperature, it must be refrigerated for at least a few hours. This pie tastes the best chilled, and it helps the filling to finish setting up properly.

Recipe Notes

• Pan: A 9-inch pie plate is used for this recipe.
• Key Lime Juice: If you cannot get fresh key limes, use bottled key lime juice for this pie. The recommended brand is Nellie & Joe’s (available at most grocery stores). While the flavor will be significantly different, you can also use regular limes or a combination of lime and lemon juice.
• Key Lime Zest: If you cannot get fresh key limes, you can substitute regular lime zest.
• Make-Ahea d: This pie can be made up to 2 days in advance. Wait to top with whipped cream until the day you serve it.
• How to Store the Pie: Refrigerate the pie, loosely covered with plastic wrap, for up to 3 days.
• Freezing Instructions: Place the entire pie, uncovered, in the freezer until completely frozen. Then wrap well in plastic wrap and then a layer of foil (or place in a freezer-safe Ziploc bag) and store in the freezer for up to 1 month. Thaw in the refrigerator overnight.

Watch the Recipe Video:

More Delicious Summer Pies

• Fresh Strawberry Pie
• Coconut Cream Pie
• The Best Blueberry Pie
• Lemon Meringue Pie
• Strawberry Rhubarb Pie
• Banana Cream Pie

If you make this key lime pie and love it, remember to stop back and give it a 5-star rating - it helps others find the recipe! ❤️️

Update Notes: This recipe was originally published in May 2012.

[photos by Ari of Well Seasoned]