These Key Lime Bars with Shortbread Crust are a delicious, refreshing twist on the classic lemon version, and strike a perfect-pucker balance between sweet and sour. They’re a cinch to make, can be made ahead, and are freezer friendly!
Key Limes vs Regular Limes
Do you have to use key limes? Of course not. Regular Persian limes will work. However, key limes, also known as Mexican or West Indian limes, are more aromatic with a more tart, floral juice. Also, the zest of a key lime has more zing.
When it comes to looks, key limes are about the size of a walnut and no larger than a golf ball, as shown below.
Plus, they have more seeds than regular limes so pour the juice through a fine strainer to make sure none sneak into the filling.
Cooking Steps & Tips
The crust is a basic shortbread dough that’s all of three ingredients. Love that! 2 TIPS to keep in mind though – First, line the baking pan with parchment paper with a two-inch overhang on each side. This will keep the bars from sticking to the pan and make it easy to transfer the whole thing to a cutting board. They are much easier to cut this way, and you’ll spare your pan a repeated assault with a sharp knife.
Second, press the dough on the bottom and about a half inch up the sides so the filling doesn’t seep down the sides and end up on the bottom of the crust resembling an inside-out pop-tart. Believe me, I know this from experience!
The crust will take on a nice golden hue once baked.
Pour the filling over and pop back in the oven!
Let the pan cool completely on a rack, then cover and chill at least one hour. The colder the tart is the cleaner the cut you’ll get when serving. Finish with a dusting of powdered sugar and you’re good to go. Enjoy!
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Key Lime Bars with Shortbread Crust
- 1 ½ sticks, (¾ cup( unsalted butter, room temperature
- 1 ½ cups flour
- ⅓ cup powdered sugar
- 3 large eggs, room temperature
- 1 ¼ cups white granulated sugar
- ¼ cup flour
- ¼ cup key lime juice, strained
- 1 teaspoon key lime zest
- ¼ teaspoon baking powder
- ⅛ teaspoon salt
- Preheat oven to 350°F. Butter bottom and sides of an 8-inch square baking dish. Line with parchment paper with 2-inch overhang.
- In a stand mixer with paddle attachment, mix butter, flour, and powdered sugar together on low speed until dough starts to form clumps.
- Flour your hands to press dough into bottom and ½-inch up sides of parchment lined baking dish.
- Bake in preheated oven until light golden brown, 20-22 minutes. Remove from oven and place on cooling rack.
- While crust bakes, beat eggs with an electric mixer on medium speed until light and foamy.
- Add sugar, flour, key lime juice, zest, baking powder, and salt. Mix until well combined. Pour key lime mixture over crust.
- Bake 22-25 minutes until edges are lightly golden and center is set.
- Cool in baking dish on rack. Then chill at least 1 hour before serving. (Can be made 2 days ahead. Keep refrigerated.)
- Use parchment paper overhang to remove from pan and cut into squares. Dust with powdered sugar and garnish with quartered lime wedges and additional zest, if desired.
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