Key Lime Tart with Marshmallow Meringue + Video

Indulge in a deliciously tangy and creamy key lime tart with this easy recipe. Follow along with the step-by-step video tutorial to create a perfect dessert for any occasion.

There is something so heavenly about a tart and tangy practically no bake dessert during the summer. The key limes mixed with sweetened condensed milk, and the sweet graham crackers crust just make me drool thinking about it! But what makes it even more delectable is the toasted marshmallow meringue on top that puts this dish over the edge. 

Plug, getting to use my own eggs from our backyard chickens is always a treat. The girls are laying 3 to 4 eggs a day, and this recipe uses both the egg yolk and the egg whites in the marshmallow meringue. The yolks from our girls are the most sunflower gold it is insane! Happy chickens definitely do lay better eggs. 

The other plus of this is that it doesn’t require you to keep your oven on for long periods of time. Really, it’s no bake, and the meringue only requires some time on a double boiler to cook the egg whites before whipping them into that beautifully soft and fluffy marshmallow meringue that is perfect for toasting with a blow torch. 

Ingredients for Key Lime Tart with Marshmallow Meringue

The ingredients here are really simple and easy to find at the grocery store. My goal is to create every day elevated recipes that are approachable and fun to create. 

Crust 

• Graham crackers, or graham cracker crumbs
• Melted Butter
• Sugar
• Pinch of Salt

Key Lime Curd Filling

• Key Lime Zest 
• Key Lime Juice
• Egg Yolks
• Whole Egg
• Sweetened Condensed Milk
• Flour
• Cream of Tar Tar
• Salt

Marshmallow Meringue

• Egg Whites
• Sugar
• Cream of Tartar
• Salt

Instructions to Make Key Lime Tart

GRAHAM CRACKER CRUST

1. Adjust an oven rack to the middle position and heat the oven to 325 degrees. Pulse the whole graham crackers in a food processor until the crackers are broken down into coarse crumbs, about eight to ten 1-second pulses. Open and stir edges to make sure no large pieces are stuck and then repeat to make fine crumbs, another 8 to 10 times.
2. Transfer the crumbs to a medium bowl or large bowl and stir in the sugar to combine; add the melted butter and toss with a fork until the crumbs are evenly moistened.
3. Use the bottom of a 1/2 cup measuring cup to press the crumbs evenly into the bottom and up the sides of a tart pan with a removable bottom, forming a crust.
4. Bake the crust until deep golden brown and fragrant, about 15 minutes. Cool the crust on a wire rack while making the filling. When cool to the touch, you can refrigerate it (covered) until you are ready to fill it.

FOR KEY LIME CURD

1. Using the same large bowl from the crust – no need to clean the bowl – whisk together the sugar, flour, cream of tartar, and salt.
2. Then whisk in the eggs and egg yolks, whisking until no white streaks from the eggs or sugar and flour remain. Continue to whisk in the lemon zest and the lemon juice.
3. Pour the mixture into a round bottomed sauce pan, and turn the stove on to medium heat. Stirring constantly, heat the mixture until it registers 160 degrees and thickens. This will ensure that the eggs are cooked through.
4. Turn off the heat, and add in the butter, one tablespoon at a time, whisking constantly until each one melts before adding the other.
5. Pour the lime curd on top of the still cooled graham cracker crust. Spread the curd evenly if needed with the back of a spoon.

MARSHMALLOW FLUFF

1. Place room temperature egg whites, sugar, and cream of tartar in a heatproof bowl – or I use the metal bowl from my standmixer. Set bowl over a saucepan filled with two inches of simmering water creating a mock-double boiler. Do not let it touch the water.
2. Whisk constantly until sugar is dissolved and mixture has thinned out, about 6 minutes. The mixture will be thick at first, then thin out and appear frothy on top because of the air that you have added to the egg whites.
3. Using an instant read thermometer the temperature should read 160°F (71°C) to ensure that the egg whites are cooked through. It may take longer than 6 minutes, depending on how fast the water in your double boiler is boiling underneath. Adjust the heat on the water as necessary.
4. Remove from heat. (No need to let it cool down before continuing.) Add the vanilla extract and salt, then using a handheld or stand mixer fitted with a whisk attachment, beat on high speed until stiff glossy peaks form, about 5 to 8 minutes. The sides of the bowl will be cool and the marshmallow fluff will be cool and glossy.
5. Meringue can be spread, piped, or swirled onto cakes, cupcakes, and other confections. Serve immediately OR torch it with a kitchen torch for a delicious toasted marshmallow topping. (Do not place in the oven under the broiler—it will melt the marshmallows and the curd.)
6. If you’re feeling super fancy you can top the marshmallow fluff with toasted shredded coconut as well and extra lime slices.

Can I use regular limes instead of key lime?

What makes key limes different than regular limes typically found in the grocery store is that they are a smaller, and more tart than Persian limes you find. The flavor is also more intense. For this recipe I highly recommend that you use fresh key limes, or regular Persian limes if that is all you can find. Please do not substitute bottled lime juice in this recipe. 

Key limes are typically famous for being from the Florida Keys, but you can find them in stores particularly in the winter when citrus is in season. 

Do I need to make the meringue?

Of course not, this tart is absolutely delightful without it, if you don’t want to make it, or don’t have a mixer on hand. A hand mixer will work, but it will take longer. Or, there is always the shortcut of using marshmallow fluff, but it may not pipe quite as well. No shame in taking shortcuts where you can! 

Is a key lime tart different than a key lime pie?

Yes, this recipe for the key lime tart creates more of a lime curd than the traditional key lime pie filling that has sweetened condensed milk in it. They are both no bake typie pies though. The traditional key lime pie also utilizes either a pie crust, or a graham cracker crust, depending on if you are a traditionalist or not. Placing them in the fridge to chill makes these perfect for the warm summer days.

Other Homemade Recipes To Try

Homemade Key Lime Curd

Meringue with Strawberry Rhubarb Sauce

20 Minute Ham and Cheese Tarts

Mud Hen Bars

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