Key Lime Pie Recipe

 This authentic Key Lime Pie recipe is easy and delicious! It has a buttery graham cracker crust and a sweet-tart creamy filling, bursting with fresh lime flavor.

💚 You’ll love this traditional key lime pie recipe

Key lime pie is the quintessential citrus dessert. It has a smooth and creamy lime filling that’s bracingly tart but not too sour – the perfect blend of sweet and tangy. It’s set atop a crisp, buttery graham cracker pie crust, and garnished with either a toasted meringue topping, or sweetened whipped cream.

This key lime pie is the real deal! The refreshing tart taste makes it a perfect summer dessert, but since limes are readily available year-round, this is one pie you can enjoy any time of year! 

Table of Contents

• 💚 You’ll love this traditional key lime pie recipe
• 🧾 What you’ll need
• 📋 How to make key lime pie
• 💭 Variations
• 💡 Tips and FAQs
• ❤️ More Desserts You’ll Love
• Key Lime Pie Recipe

The secret to authentic key lime pie

The creamy custard filling in an authentic key lime pie has 3 main components:

• egg yolks
• sweetened condensed milk
• key lime juice

This may seem like an unusual combination, until you understand the origins of this classic American dessert. 

Key lime pie originated in Key West, Florida in the late 1800s. Key limes are plentiful in the Florida Keys, so it was a natural choice to use their juice. And since fresh milk and access to refrigeration weren’t readily available, people had to utilize canned milk, hence the sweetened condensed milk in this recipe.

What are key limes?

“Regular” limes, or Persian limes, are the limes we typically see in grocery stores. They’re larger, with a thicker peel and dark green skin. 

Key limes, also known as Mexican limes or West Indian limes, are small, round limes with a yellow-green color, thin skin, and a bright, intense lime flavor. 

For lots more information about key limes, don’t miss our detailed post about the difference between regular limes and key limes!

Depending on where you live, key limes might be difficult to find in stores. If that’s the case, it is completely fine to substitute fresh Persian lime juice for key lime juice. I recommend using fresh lime juice over bottled key lime juice whenever possible.

🧾 What you’ll need

Key lime pie ingredients & substitutions

A few notes on the ingredients you’ll need for this pie: (Links are affiliate links and I earn a small commission from qualifying purchases.)

• Lime juice: fresh key lime juice is traditionally used to make this pie. You will need about 18-20 key limes to get the 1 cup of juice required for this recipe. Look for limes that are heavy for their size, and have a little give when you squeeze them. Can’t find key limes? That’s okay – the most important thing is that you use fresh lime juice of some kind. (Bottled juice is available, but not recommended–it typically has a harsh, sour, chemical flavor.) Fresh Persian lime juice is a great alternative and works well in this recipe. You will need about 5 large Persian limes to get 1 cup of juice.
• Lime zest: fresh lime zest adds an extra punch of lime flavor, as well as beautiful specks of green throughout the pie filling. Use a microplane to zest your limes before juicing them.
• Sweetened Condensed Milk: make sure you use sweetened condensed milk—not evaporated milk or another type of canned milk. The cans look similar and they’re usually in the same section at the grocery store, but they are not the same thing and won’t give you the same results.
• Egg yolks: This recipe uses six egg yolks. Here’s my full guide to separating egg yolks and whites if you need a refresher, and don’t forget to save the egg whites for a future batch of Meringue Cookies or buttercream!
• Graham crackers: you’ll need about 10 rectangular graham crackers to get the 1.5 cups/6 ounces of crumbs needed for the graham cracker crust. I love using a homemade graham cracker crust, but you can also use a pre-made graham cracker crust if you prefer.

Equipment

• Microplane: you can use a microplane to easily zest the limes. If you don’t have a one, a cheese grater will work as well.
• Juicer: squeezing by hand works, but you don’t get nearly as much juice out of the limes. I recommend using a countertop juicer to maximize the juice you get out of your fruit.
• Pie pan: use a 9 x 1.5″ pie plate for a deep-dish crust that can hold all the filling.
• Piping bag and Star tip: I like these disposable piping bags (I wash them and re-use them to reduce waste!) and used a large star tip to make the whipped cream rosettes.

📋 How to make key lime pie

Here’s a quick overview of how to make the graham cracker crust and key lime pie filling for this easy key lime pie recipe. Scroll below for the printable instructions and ingredient measurements, and check out the embedded video for a step-by-step walkthrough.

Make the sweet graham cracker crust

• Crush the graham crackers in a food processor until they are fine crumbs, or put them in a zip-top bag and roll over them with a rolling pin until crushed.
• Combine graham cracker crumbs, melted butter, granulated sugar, and salt in a medium bowl.
• Stir everything together until it’s well-combined and the texture of wet sand.

• Press the crust mixture evenly on the bottom and up the sides of your pie pan.
• Bake at 350ºF for 15 minutes. Allow it to cool completely on a wire rack before adding the filling.

Make the key lime pie filling

• Zest the fresh key limes with a microplane until you have 2 tablespoons of fresh zest.
• Juice the limes and measure out 1 cup of juice.

• In a large mixing bowl, whisk together egg yolks and sweetened condensed milk.
• Add the fresh lime juice and zest to the bowl.

• Whisk the lime juice, zest, and a bit of salt into the filling, and stir until it’s thick and smooth.

• Pour the filling into the baked and cooled graham cracker crust, and bake at 350ºF for 20 minutes.
• The pie is done when the center barely jiggles when you move the pan.
• Let the pie cool at room temperature, then refrigerate for at least 6 hours so it sets up completely.

Decorate the pie

• Combine heavy whipping cream and powdered sugar in the bowl of a stand mixer fitted with a whisk attachment and whip on medium-high speed until the cream is thick and holds medium-stiff peaks.
• Transfer the mixture to a piping bag with a star tip and pipe rosettes around the outer edge of the pie.
• Finish with a sprinkling of lime zest and a twist of lime in the center.
• Slice, serve, and devour!

💭 Variations

Wanting to switch things up? Here are a couple suggestions:

• Use store-bought crust. If you want to save a little bit of time, you can use a store-bought graham cracker crust. However, store-bought crusts might be shallower than homemade crust, so you may end up with a little extra key lime filling.
• Try a different crust flavor. Instead of graham crackers, try using shortbread cookies, gingersnaps, or crunchy coconut cookie crumbs.
• Go for meringue. Try toasted meringue instead of whipped cream for the topping.
• Switch up the citrus. Most sour citrus fruit will work in this recipe, and produce a delicious creamy sweet-tart filling. Lemon is a natural choice, but grapefruit is delicious too! If you want to make this with orange, I suggest using half orange and half lemon juice, since oranges are much sweeter and the pie needs some of lemon’s sourness to balance it out.

💡 Tips and FAQs

Here are a few of my tips to make the best key lime pie!

• Use freshly squeezed juice. Bottled juice contains preservatives that can make the juice taste “off” or slightly stale. I recommend freshly squeezing the lime juice for the best flavor!
• Pre-bake the crust. While graham cracker crusts can sometimes be used without baking, this pie is best with a pre-baked crust. The extra baking time ensures the graham crust doesn’t get soggy.
• Let the crust cool. After you pre-bake the crust, let it cool completely before you add the filling so it has time to firm up.
• Use a 2-inch deep pie pan. This recipe makes enough filling to fill a deep dish crust, so I recommend using a 2-inch deep pan.
• Chill the pie. After the pie is prepped and baked, chill it in the fridge overnight (or for at least 6 hours) before you cut into it so it can set.

❤️ More Desserts You’ll Love

• Graham Cracker Crust
• Toasted Coconut Lime Meringue Tart
• Grapefruit Tarts
• Orange Bundt Cake
• Lemon Meringue Teacup Cakes
• Lime Coconut Pie