Citrus lovers will be wild about these luscious Key Lime Shortbread Bars! They have a buttery, flaky crust, they’re bursting with fresh key lime flavor, and they’re so easy to make!

Key lime shortbread bars stacked on top of each other.

Sometimes the best recipes come to be by accident. These Key Lime Bars were supposed to be lemon bars, but I realized last minute that I didn’t have enough lemons.

A friend was visiting who loves lemon bars, and I thought this recipe would be just as good (if not better) with key limes. I went ahead and baked this key lime version, and they were a huge success.

The fact that I often have fresh key lime juice stashed in my refrigerator or freezer speaks volumes about how much I love it. I always have it to make our family favorite key lime pie recipe!

These key lime shortbread bars take just 15 minutes to assemble, and are a fabulous make-ahead dessert that can be enjoyed throughout the spring and summer.

They’re sweet, tangy and absolutely irresistible. 🙂

Key lime bars cut into squares with powdered sugar.
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Why you’ll love this recipe

  • Key lime shortbread bars have a tangy, sweet key lime filling, buttery shortbread crust, and they’re topped with a dusting of powdered sugar.
  • This recipe requires minimal ingredients and comes together in 15 minutes.
  • It’s a flexible recipe that will work with any citrus that you have on hand.  

Recipe Ingredients

This recipe only requires six simple ingredients as outlined below.

  • Unsalted Butter. Using unsalted butter allows you to control the sodium. Allow the butter to soften at room temperature before preparing the crust.
  • All purpose flour. The flour is used in the crust, and a small amount is used to thicken the filling as well.
  • Powdered sugar. Powdered sugar provides the bars with their trademark powdery white topping, and it’s also used to sweeten the crust. Powdered sugar contains cornstarch, which gives the crust a soft, melt in your mouth texture.
  • Granulated sugar. This is used to sweeten the key lime filling.
  • Fresh key limes. You’ll need both zest and the juice for these key lime bars. The key lime juice is the star of these bars, and fresh juice makes all the difference. It’s got a bright, fresh flavor that bottled key lime juice just can’t provide. 
  • Eggs. The eggs give the filling structure and a custard-like richness.

See the recipe card below for the full list of ingredients and quantities.

How to make key lime bars with shortbread crust

This recipe is very easy to make and it comes together in about 15 minutes.

Pro tip: Place the butter and eggs on the counter to come to room temperature up to 30 minutes in advance. Cutting the butter into small pieces and placing the eggs in warm water will speed up the process. 

See the recipe card below for full instructions.

Unbaked shortbread crust for key lime bars.
Prepare shortbread crust and spread evenly in prepared pan.
Baked shortbread crust for key lime bars.
Bake the crust for 20-25 minutes until golden.
Whisk eggs and sugar for key lime bar filling.
Whisk eggs and sugar in a large bowl.
Filling for key lime bars.
Whisk in the flour until incorporated, then whisk in key lime zest and juice.
Key lime shortbread bars before baking.
Pour the filling over the crust and bake for 20-25 minutes.
Dust cooled key lime shortbread bars with powdered sugar.
Cut cooled bars into squares and dust with powdered sugar.

Recipe FAQs

What’s the difference between key limes vs regular limes?

Key limes are smaller and contain more seeds than regular limes, but the main difference is the flavor. Key limes are aromatic with a special flavor that’s tart and floral.

Note that it takes about 20 key limes to produce 1/2 cup or more of juice.

How can you tell when key lime bars are done?

The bars are done when the filling is completely set.  Move the pan gently back and forth — the filling should not “wiggle.” Do not over bake as this will result in the filling cracking.

How do you cut the bars cleanly?

The most important thing is to make sure that the bars have cooled completely, and cut before dusting them with powdered sugar. Use a very sharp knife, wiping the knife clean in between slices.

How long will the bars last? Should they be refrigerated?

You’ll need to refrigerate leftover key lime shortbread bars in an air tight container. They’ll last up to 5 days.

Key lime bars with powdered sugar and lime slice on top.

Recipe notes

  • Pro tip: Place the butter and eggs on the counter to come to room temperature up to 30 minutes in advance. Cutting the butter into small pieces and placing the eggs in warm water will speed up the process. 
  • You can juice the key limes up to 2 days in advance, and either refrigerate or freeze it until you’re ready to make the bars.
  • You can easily substitute the key lime juice with any type of citrus juice. Freshly squeezed lemon, orange, blood orange, or grapefruit juice are all great options.
Stack of key lime shortbread bars with lime slice on top.

More key lime recipes you’ll love

Did you try this recipe?  If so, be sure to leave a review below and tag me @flavorthemoments on Facebook and Instagram

Key lime shortbread bars stacked on top of each other.

Key Lime Shortbread Bars Recipe

Servings: 9 bars
Prep Time: 15 minutes
Cook Time: 50 minutes
Cooling Time: 2 hours
Total Time: 3 hours 5 minutes
A creamy key lime filling tops a buttery shortbread crust in these easy key lime shortbread bars.
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Equipment

Ingredients

For the shortbread crust:

  • 1/2 cup unsalted butter softened
  • 1/4 cup powdered sugar
  • 1 cup all purpose flour
  • 1/4 teaspoon salt

For the filling:

  • 3 large eggs
  • 1 cup granulated sugar
  • 3 tablespoons all purpose flour
  • 1 tablespoon lime zest
  • 1/2 cup key lime juice
  • 1/2 cup sifted powdered sugar for garnish

Instructions 

  • Preheat oven to 350 degrees. Line an 8×8" baking dish with parchment paper or foil.
  • Prepare the crust. In a large bowl, beat the butter and 1/4 cup powdered sugar till light and fluffy, about 2-3 minutes. Add flour and salt, and beat on low speed until just incorporated.
    1/2 cup unsalted butter, 1/4 cup powdered sugar, 1 cup all purpose flour, 1/4 teaspoon salt
  • Scrape the dough into the prepared pan and spread evenly with an offset spatula. Bake on the middle rack of the oven 20-25 minutes, or until lightly golden. Remove from the oven and cool on a wire rack while you prepare the filling.
  • Prepare the filling. In a medium bowl, whisk the eggs and granulated sugar until well incorporated. Add the 3 tablespoons of flour and whisk until combined, then whisk in the lime juice and zest.
    3 large eggs, 1 cup granulated sugar, 3 tablespoons all purpose flour, 1 tablespoon lime zest, 1/2 cup key lime juice
  • Pour the filling over the cooled crust, and bake 20-25 minutes longer, or until the filling has set. The filling will not "wiggle" when the pan is moved gently back and forth. Remove from heat and cool completely on a wire rack.
  • Once the key lime bars have cooled, cut into squares with a sharp knife, wiping the knife clean in between slices. Dust with powdered sugar, serve and enjoy!
    1/2 cup sifted powdered sugar

Notes

  • Pro tip: Place the butter and eggs on the counter to come to room temperature up to 30 minutes in advance. Cutting the butter into small pieces and placing the eggs in warm water will speed up the process. 
  • Cut the bars into smaller portions to serve more guests as desired.
  • Swap out the key lime juice for regular lime, lemon, orange and more!
  • Store at room temperature for up to 2 days or in the refrigerator for up to 5 days.

Nutrition

Serving: 1bar, Calories: 312kcal, Carbohydrates: 48g, Protein: 4g, Fat: 12g, Saturated Fat: 7g, Polyunsaturated Fat: 4g, Cholesterol: 89mg, Sodium: 85mg, Fiber: 1g, Sugar: 35g

Nutrition is estimated using a food database and is only intended to be used as a guideline for informational purposes.

Course: Sweets
Cuisine: American
Author: Marcie
All recipes and images © Flavor the Moments.
Did you try this recipe?Be sure to tag @flavorthemoments with the hashtag #flavorthemoments on Instagram so I can see what you made!

**This recipe was originally published in August 2013.  The photos and text have been updated and step by step photos have been added.

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