Key Lime Pie Bars

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Key lime pie - it's tart and sweet and fresh! My recipe for Key Lime Pie Bars is so simple to make and easy to serve in bar form instead of slicing up a pie. There is a crisp buttery graham cracker crust, super creamy and silky rich lime custard filling and a thick layer of fresh whipped cream.

WHY YOU WILL LOVE THIS RECIPE

Easy to make - this recipe is very simple and you only need 2 egg yolks and one whole egg so you won't have a ton of leftover egg whites.
Not too sweet - this recipe makes bars that are tart and with a balanced sweetness. If you like desserts that aren't too sweet, you will love these.
Creamy smooth filling- the filling is so silky smooth since it's made with sweetened condensed milk the traditional way, and it's baked gently.
Fresh lime flavor - there's lime zest in the custard and on top of the cream to garnish, and also plenty of fresh lime juice for that tangy fresh flavor.
Graham cracker crust - just like the traditional classic key lime pie, this recipe uses a simple graham cracker crust made from just 3 simple ingredients.

INGREDIENTS

Graham crackers - you'll need about 1 sleeve or 24 individual graham crackers to make the crust.
Brown sugar - a bit of brown sugar helps the crust bind together a bit better.
Butter - melted butter will bring the graham cracker crumbs together to form a base. If you like saltiness, you can use salted butter here.
Sweetened condensed milk - you will need about half a can of sweetened condensed milk. It keeps forever in the fridge due to it's high sugar content, so just transfer the rest to an airtight container and you can keep it for at least a month for another use. I love to put it in my tea or coffee!
Egg - one whole egg will set the filling into a silky smooth custard. After all, cheesecake is essentially a baked cheese custard!
Egg yolk - traditional key lime filling uses a lot of egg yolks, but I find many people do not have a use for the whites and they think it is wasteful. So, I've designed this recipe to use just two large egg yolks. Yolks are necessary to add the silky richness and yellow color of the custard.

Yogurt - full fat plain yogurt adds creamy, tangy dairy notes and also lightens it up for an extra silky texture. You can also use Greek yogurt or sour cream for this recipe.

Pure vanilla extract - vanilla boosts the creamy flavor and carries the lime flavor really nicely. I prefer this Madagascar Bourbon Vanilla extract.
Granulated sugar - simple fine white granulated sugar in the filling keeps the flavor clean so the lime shines.
Lime juice and lime zest - lime juice and zest is used to make the custard filling and extra lime zest is a nice garnish on top.
Heavy cream or whipping cream - for the topping, all you need is pure cream with 35% milk fat and a tiny bit of icing sugar. It makes the most thick and luscious cloud-like cream on top!

STEP BY STEP INSTRUCTIONS

This recipe is super simple. I recommend using an electric hand mixer for best results.

STEP 1). Make the crust. Break graham crackers into rough pieces and place in a food processor fitted with a blade attachment. Pulse until it forms fine crumbs similar to bread crumbs. Add brown sugar and melted butter and pulse again until it looks like damp sand.
STEP 2). Bake the crust. Transfer the mixture to the prepared pan and use your hands or the bottom of a measuring cup to press it into the bottom of the baking pan in an even layer. Bake for about 15 minutes until fragrant and starting to darken around the edges.
STEP 3). Lower the oven. Reduce oven temperature to 325°F.
STEP 4). Make the filling. Combine sweetened condensed milk, whole egg and egg yolks into a large bowl and whisk until smooth.
STEP 5). Mix in lime juice and yogurt. Mix in lime juice. Add yogurt and lime zest and mix well. Finally, mix in sugar.

BAKING & CHILLING

STEP 6). Bake. Gently pour the mixture over the baked crust and spread in an even layer (it’s okay if the crust is still slightly warm). Bake for 15-20 minutes until the filling is just set and still a little jiggly in the center.
STEP 7). Chill. Transfer pan to a wire rack to cool completely. Cover and refrigerate for at least 4 hours or up to overnight.
STEP 8). Make the topping. Place cold heavy cream in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Beat with the whisk attachment on medium speed until slightly thickened. Add 1 tablespoon powdered sugar and continue beating until stiff peaks form, 1 to 2 minutes more. Spread the whipped cream over the bars. Run a knife around the edges of the pan. Grasping the parchment sling, lift the key lime bar slab out of the dish and onto a cutting board. Grate some lime zest over top just before serving and then cut into squares. Serve chilled.

EXPERT TIPS:

Use fresh lime juice. This is so important! Fresh citrus tastes so much brighter than bottled juice because bottled juice has been heat-processed in order to be food-safe.

Don't squeeze the limes to firmly. This is important especially if you don't have key limes and you use regular limes. The pith (the white part) of limes is very bitter and if you squeeze too much to extract every drop of juice, then you will also extract flavors from the pith. Key limes are sweeter than regular limes, so it is less of an issue if you have access to them.

Use room temperature eggs. A cold egg will not incorporate as smoothly. Room temperature eggs will ensure the custard is silky smooth.

Do not over-beat. Over-mixing or mixing at a very high speed will incorporate too much air into the mixture which will create air bubbles that float to the surface of the custard layer.

Gentle baking. To ensure the filling is extra silky smooth, it is important bake these gently at a slightly lower than moderate temperature.

RECIPE FAQ

How do I know when my key lime pie bars are baked correctly?

The key to making silky smooth key lime pie is to be careful not to over bake it. Once the edges are set and the middle is has a slight wobble, then it is ready. The residual heat will continue to gently cook the filling as it cools.

What is a substitute for yogurt in key lime pie bars?

You can also make this recipe using an equal amount of full fat or light sour cream. Another suitable substitution is crème fraîche - a type of fermented dairy product somewhere between yogurt and sour cream.

What if I don't have key limes? Can I substitute limes for key limes?

You don't need Key limes to make key lime pie! You can use regular limes.

What is the difference between Key limes and regular limes?

Key limes are smaller and sweeter than regular limes, and they are grown in the Florida Keys. They also have less pith (the bitter white part in the peel). To make sure you get the same great taste with regular limes, make sure you don't squeeze the limes too hard, otherwise you will also extract undesirable bitter flavors from the pith. A tip for squeezing limes to get the most juice: roll the lime under your palm over the countertop to burst the juice-containing cells and make it easier for the juice to come out.

Do I need to chill key lime pie bars after it bakes?

Yes it is important to let the bars chill in the fridge for at least 2 hours (ideally 4 hours) before serving. This cooling time will allow the custard to set completely for the silkiest texture.

How to get clean slices on these key lime pie bars?

Let the bars cool completely and then refrigerate for at least 4 hours before slicing for the best texture and cleanest slices.

How do I store key lime pie bars?

These bars should be stored in the refrigerator in an airtight container for up to 5 days. The crust will soften after the 2nd day.

How do I serve key lime pie bars?

These bars are lovely served just as it is, but if you want to jazz it up even more, you can add some fresh berries.

Can I freeze key lime pie bars?

I would not recommend freezing these bars as the crust will become soggy and the filling may curdle as it thaws.

Looking for more bar recipes like this? Try these:

Baking with citrus

Here are more citrusy recipe ideas:

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Christina Marsigliese

Tart and sweet and extra creamy "Key" lime pie bars with a graham cracker crust and thick layer of fresh whipped cream. These are easy to make and easy to serve!

5 from 5 votes

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Prep Time 15

Cook Time 35

Chill Time 4

Servings 12 bars

Ingredients

Crust:

24 graham crackers about 7oz/200g, or 1 ½ cups graham cracker crumbs
2 tablespoon 30g packed light brown sugar
⅓ cup 75g unsalted butter

Filling:

½ cup 6oz/170ml sweetened condensed milk
1 large whole egg
2 large egg yolks
1 teaspoon 5ml pure vanilla extract
½ cup 120ml lime juice
⅓ cup 80ml full fat yogurt
zest of 1 lime
¼ cup 50g granulated sugar

Topping:

1 cup cold heavy cream
1 tablespoon powdered sugar
lime zest to garnish

Instructions

Preheat the oven to 350°F. Line an 8x8-inch metal baking pan with parchment paper leaving an overhang of about 2 inches on the sides for easy removal.
First make the crust. Break graham crackers into rough pieces and place in a food processor fitted with a blade attachment. Pulse until it forms fine crumbs similar to bread crumbs. Add brown sugar and melted butter and pulse again until it looks like damp sand. Transfer the mixture to the prepared pan and use your hands or the bottom of a measuring cup to press it into the bottom of the baking pan in an even layer. Bake for about 15 minutes until fragrant and starting to darken around the edges.
Meanwhile, make the filling. Combine sweetened condensed milk, whole egg, egg yolks and vanilla into a large bowl and whisk until smooth. Mix in lime juice. Add yogurt and lime zest and mix well. Finally, mix in sugar. Gently pour the mixture over the baked crust and spread in an even layer (it’s okay if the crust is still slightly warm).
Reduce oven temperature to 325°F and bake for 15-20 minutes until the filling is just set and still a little jiggly in the center. Let cool completely on a wire rack. Cover and refrigerate for at least 4 hours or up to overnight.
Make the topping. Place cold heavy cream in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Beat with the whisk attachment on medium speed until slightly thickened. Add 1 tablespoon powdered sugar and continue beating until stiff peaks form, 1 to 2 minutes more. Spread the whipped cream over the bars. Run a knife around the edges of the pan. Grasping the parchment sling, lift the key lime bar slab out of the dish and onto a cutting board. Grate some lime zest over top just before serving and then cut into squares. Serve chilled.