Citrus fans will love these Key Lime Shortbread Bars. They combine a tender, buttery shortbread crust with a bright, creamy key lime filling and a light dusting of powdered sugar. They’re simple to assemble, refreshingly tangy, and a perfect make-ahead dessert for spring and summer gatherings.
These bars were a happy kitchen detour: intended as lemon bars, I didn’t have enough lemons on hand and swapped in key limes instead. The result was a bright, floral-tart filling paired with a melt-in-your-mouth shortbread crust—and it was an instant hit with guests.
I keep fresh key lime juice in the fridge or freezer because the flavor is so special. Freshly squeezed juice gives the filling a brightness that bottled juice can’t match. If you already enjoy key lime pie, you’ll find these bars to be the same refreshing flavor in an easy, hand-held form.
They take only about 15 minutes to assemble, then bake and cool. They’re easy to make ahead and store well refrigerated for several days.
Why you’ll love this recipe
- Bright and tangy key lime filling balanced by a rich, buttery shortbread crust and a dusting of powdered sugar.
- Few ingredients and a quick 15-minute assembly make it an easy, approachable dessert.
- Flexible—you can substitute other citrus juices (lemon, regular lime, orange, or grapefruit) if desired.
Recipe Ingredients
This recipe uses six simple ingredients. The crust is shortbread-style, while the filling is a custard-like mixture brightened with fresh key lime zest and juice.
- Unsalted butter — softened so you can cream it with the powdered sugar for the crust.
- All-purpose flour — used for the crust and a small amount to thicken the filling.
- Powdered sugar — sweetens the crust and provides the classic powdered finish on top.
- Granulated sugar — sweetens the filling.
- Fresh key limes — you’ll need zest and juice; fresh juice yields the best flavor.
- Eggs — give the filling structure and a custard-like texture once baked.
See the recipe card below for exact quantities and step-by-step instructions.
How to make key lime bars with shortbread crust
These bars are straightforward: make the shortbread crust, bake it briefly, pour on the filling, then bake again until set. Total hands-on time is short and the method is forgiving.
Pro tip: Bring butter and eggs to room temperature for up to 30 minutes before you start. Cutting butter into small pieces and placing eggs in warm water speeds the process.
Full instructions are included in the recipe card below.
Recipe FAQs
Key limes are smaller and have a distinct aromatic, tart, and slightly floral flavor compared with common Persian limes. They also tend to have more seeds. Fresh key lime juice has a unique brightness that works especially well in desserts.
The bars are finished when the filling is set and no longer “wiggles” when you gently move the pan. Avoid overbaking, which can cause cracking in the filling.
Allow the bars to cool completely, then slice before dusting with powdered sugar. Use a very sharp knife and wipe it clean between cuts for neat edges.
Store leftover bars in an airtight container in the refrigerator for up to 5 days. They can be kept at room temperature for up to 48 hours, but refrigeration is recommended for the best texture and freshness.
Recipe notes
- Make-ahead: You can juice key limes up to two days in advance and refrigerate (or freeze) the juice until needed.
- Substitutions: The recipe works well with other citrus juices—fresh lemon, regular lime, orange, or grapefruit will all produce excellent variations.
- Serving tips: Cut into smaller squares to serve more people, and dust with powdered sugar just before serving.
- Storage: Keep at room temperature for up to 48 hours or refrigerated for up to 5 days.
More key lime recipes you’ll love
- Key lime cheesecake bars with a coconut-macadamia crust
- Key lime cookies
- Fresh key lime Greek yogurt fruit dip
Did you try this recipe? If so, please leave a review below and tag @flavorthemoments on Facebook or Instagram so I can see what you made.
Key Lime Shortbread Bars Recipe
Equipment
- 8×8″ baking pan lined with parchment or foil
- Offset spatula (helpful for spreading the crust)
- Mixing bowls and whisk
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 (freshly squeezed)
- 1/2 cup sifted powdered sugar for garnish
Instructions
- Preheat the oven to 350°F (175°C). Line an 8×8″ baking dish with parchment paper or foil, leaving some overhang for easy removal.
- Prepare the crust: In a large bowl, beat the softened butter with 1/4 cup powdered sugar until light and fluffy, about 2–3 minutes. Add 1 cup flour and 1/4 teaspoon salt, and mix on low until just combined.
- Press the dough evenly into the prepared pan using an offset spatula. Bake on the middle rack for 20–25 minutes or until the edges are lightly golden. Remove and cool on a wire rack while you make the filling.
- Prepare the filling: In a medium bowl, whisk together the eggs and granulated sugar until well combined. Whisk in 3 tablespoons flour, then stir in the lime zest and key lime juice until smooth.
- Pour the filling over the cooled crust and return to the oven. Bake 20–25 minutes more, or until the filling is set and no longer wobbly when the pan is moved gently.
- Cool the bars completely on a wire rack. Once cooled, use a sharp knife to cut into squares, wiping the knife clean between slices. Dust with sifted powdered sugar just before serving.
Notes
- Bring butter and eggs to room temperature before starting for best texture.
- Fresh key lime juice makes the best-tasting filling; you can juice in advance and refrigerate or freeze the juice.
- Variations: swap key lime juice for lemon, regular lime, orange, or grapefruit juice.
- Storage: keep at room temperature up to 48 hours or refrigerate up to 5 days.
Nutrition (per bar)
Serving: 1 bar — Calories: 312 kcal; Carbohydrates: 48 g; Protein: 4 g; Fat: 12 g; Saturated Fat: 7 g; Cholesterol: 89 mg; Sodium: 85 mg; Fiber: 1 g; Sugar: 35 g.
Note: This recipe was originally published in August 2013. Photos and text have been updated and step-by-step images have been added to make the method easier to follow.