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These easy Key Lime Bars are an ideal treat to share at summertime potlucks and picnics! Everyone will love the creamy, zesty, sweet-and-tart key lime pie filling resting atop a buttery graham cracker crust. You only need 6 main ingredients and 30 minutes!
As temperatures rise, cooling desserts like these key lime bars are just what you need. The balance of sweet and tart flavors in the velvety filling from condensed milk and key lime juice is perfect, and the easy graham cracker crust adds crunch. They’re basically key lime pies in bar form!
Zingy key lime pie bars are a great make-ahead dessert. Since they need to chill for a few hours before slicing, you can bake them the night before you need them and pop them into the fridge to chill overnight. That way, when you slice them, the process is totally mess-free, and the bars will be neat squares every time. For more dessert bar recipes, try my cheesecake bars, lemon bars, and s’mores bars.
6 Key Ingredients
You only need a handful of ingredients to make these creamy key lime bars! Find the full ingredient list with measurements in the recipe card.
Crust — for the buttery graham cracker crust, you need graham crackers, granulated sugar, and melted unsalted butter.
Egg yolks — egg yolks help the custard-like filling set and also add lots of richness.
Condensed milk — sweetened condensed milk adds sweetness to balance the tart key lime juice and also contributes to the filling’s velvety texture.
Key limes — key limes are tiny, extra flavorful limes that are strongly associated with the Florida Keys, where they grew abundantly. For this recipe, you need key lime juice and zest.
Key Lime Bars Recipe
Equipment
- 8×8 inch pan
- Parchment paper
- Handheld electric mixer or stand mixer with whisk attachment
Ingredients
For the Crust:
- 1½ cups graham cracker crumbs (180g), from 11 large graham cracker sheets
- ¼ cup granulated sugar (50g)
- ¼ teaspoon salt
- 6 tablespoons unsalted butter melted (85g)
For the Filling:
- 3 large egg yolks
- 1 (14-ounce/396g) can sweetened condensed milk
- ½ cup key lime juice (120mL)
- 1 teaspoon lime zest plus more to serve
To Serve (optional):
- 2 cups whipped cream
- 2 key limes thinly sliced
Instructions
- Preheat the oven to 350°F. Grease an 8×8-inch pan with butter or nonstick spray. Line the pan with parchment paper, leaving a 2-inch overhang on at least two sides.
- In a large bowl, combine the graham cracker crumbs and sugar. Drizzle the melted butter all over and stir well to combine. Pinch the mixture between your fingers and thumb. If it holds together on its own, the crust is ready. If it is sandy and falls apart, add 1 more tablespoon of melted butter and stir to combine.)
- Place the mixture in the prepared baking pan. Use a flat-bottomed glass or measuring cup to firmly press the mixture into the bottom of the pan. Bake for 10 to 12 minutes, until golden brown around the edges and dry all over. Set aside to cool slightly.
- Decrease the oven temperature to 325°F.
- In a large mixing bowl with an electric mixer, beat the egg yolks for 1 minute until slightly thickened and lighter in color. Add the sweetened condensed milk and mix well to combine. Mix in the key lime juice and zest. Pour the filling over the crust.
- Bake for 12 to 15 minutes until the filling is just set. Remove from the oven and let cool to room temperature. Refrigerate for 4 hours until well chilled.
- Serve the bars with whipped cream, if you like. You can spread it over top of the bars in a thin layer, then slice and serve. Or, slice the bars and serve with a dollop of the whipped cream. Garnish with a slice of key lime or a sprinkle of lime zest.
Notes
- Make a parchment sling in the baking pan. Make sure there parchment paper has a 2-inch overhang on at least two sides of the baking pan to make removing the chilled dessert bars easy. Use the overhang as handles to lift them out.
- Use regular sweetened condensed milk. You can find non-dairy alternatives like condensed coconut milk, but they sometimes don’t set as well as the dairy version, and the bars may not slice well.
- Don’t press anything to the surface of the bars for storage. Plastic wrap will stick to the bars and damage the smooth top. I typically cover the top of the pan with a large sheet of aluminum foil if I’m chilling the bars for a longer period of time. The foil is sturdy and won’t sag to touch the bars!
Nutrition
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How To Make Key Lime Bars
1. Add the graham cracker crumbs and sugar to a large bowl. Drizzle in the melted butter and stir well.
2. Pinch the crust mixture between your fingers and thumb. If it holds together, move on to the next step. If it falls apart, add more melted butter and try the pinch test again.
3. Transfer the crust mixture into a greased 8×8-inch square baking pan lined with parchment paper. Press the crust into the bottom of the pan. Bake the crust at 350°F for 10 to 12 minutes and set the crust aside to cool while you work on the key lime pie bars filling.
4. Beat the egg yolks with an electric mixer in a large mixing bowl until thickened. Add the condensed milk and mix well.
5. Pour in the key lime juice and add the zest, then mix to incorporate.
6. Pour the filling over the crust and spread it into an even layer. Bake the dessert bars at 325°F for 12 to 15 minutes or until the filling is just set. Remove from the oven and let the unsliced key lime bars cool to room temperature in the pan set on a wire rack. Chill for at least 4 hours before slicing.
Should I Use Fresh Or Bottled Key Lime Juice?
In this recipe, fresh key lime juice will definitely have the best flavor. But you can use bottled key lime juice if needed or if you can’t find fresh key limes. My preferred brand of bottled juice is Nellie & Joe’s Key West Lime Juice, which you can usually find at major grocery stores with the other shelf-stable juices. Alternatively, feel free to just use regular limes! They are slightly more tart than key limes, but no one will be the wiser!
Making The Crumb Crust
Use a food processor to pulverize graham cracker sheets into fine crumbs. Or, place them in a zip-top plastic bag and crush them with a rolling pin to make fine crumbs. You can also use a box of ready-made graham cracker crumbs. Don’t skip the pinch test if you opt for ready-made crumbs. They may require more butter to form a crust than freshly crushed graham crackers.
You can also get creative with the crust. Instead of a classic graham cracker crust, you can use different cookies like Biscoff, gingersnaps, or other flavors of graham crackers for variety and a twist on the flavor of these key lime pie bars.
How To Serve
Just like my classic key lime pie, whipped cream pairs beautifully with key lime bars. You can spread it all over the bars in a thin layer before slicing, or serve each sliced bar with individual dollops of whipped cream. Add a sprinkle of lime zest or a thin slice of key lime as a garnish. Alternatively, generously sprinkle key lime dessert bars with powdered sugar and serve.
How To Store
Key lime bars will keep well in the refrigerator in an airtight container for up to 5 days. (But between you and me, they’re usually devoured long before then!)
Pro Tips For Making This Recipe
- Chill the bars before slicing. This will ensure the slices are neat every time. You should also use a sharp knife and wipe it clean between slices so there aren’t any crumbs transferred to the filling from the crust.
- Make it in advance. Since the bars need a few hours to chill, you can make the bars until the end of Step 6 a night ahead and refrigerate them overnight. That way, all that’s left to do is slice, garnish, and serve!
Frequently Asked Questions
Yes, key lime bars can be frozen for up to 3 months in an airtight freezer container. The texture of the filling might slightly change when thawed, so I recommend serving them still partially frozen. They make a delicious cooling summertime treat!
Yes, just double the recipe. The key lime bars will be slightly thicker, so bake them for at least 15 minutes or until the filling is set.
Yes! While 12 to 15 minutes may seem like a very short time, part of the magic of key lime filling is that the acid from the limes reacts with the egg yolks and sweetened condensed milk. This combo of ingredients naturally sets up with just a touch of heat added, so unlike a typical custard pie, you don’t need to bake it for a long time.
If you’ve tried this key lime bars recipe, then don’t forget to rate it and let me know how you got on in the comments below. I love hearing from you!
