Lemon-Lime Bars

For anyone who wants more tang from classic lemon bars, you’re missing the secret ingredient: limes. Limes are sharper and more sour than lemons, so we add that flavor in the shortbread crust and custard filling for these lemon-lime bars. That secret ingredient bakes up so these bars have a craveable, heady tang that makes a mouth pucker—but not overpoweringly so. (If that’s what you’re after, though, then skip the confectioners’ sugar topping.)

Ingredients for Lemon-Lime Bars

• Crust: Our lemon-lime squares have a classic shortbread crust, not a graham cracker crust. To make it, you’ll need butter, all-purpose flour, confectioners’ sugar, salt and a little lime zest.
• Eggs: We whip up a homemade lemon-lime curd for these bars, so you’ll need eggs to give the bars that custard-like filling.
• Sugar: Between the lemons and limes, there are a lot of sour flavors in these bars. A good amount of granulated sugar balances them out.
• All-purpose flour: Flour helps the egg yolks thicken the lemon-lime custard filling.
• Baking powder: We use a little baking powder to help the filling puff up just a bit.
• Lemon juice: Always use fresh lemon juice for the purist, cleanest lemon flavor. You’ll need about two lemons to get 1/3 cup juice. Always measure, though, as some lemons are juicier than others!
• Lime zest: Be careful not to grate too far down into the peel. The outermost part of a citrus fruit has the most desirable flavor, while the lighter-colored inner part of the peel (the pith) tastes bitter.
• Confectioners’ sugar: To balance out the sourness, finish the lemon-lime bars with a generous dusting of confectioners’ sugar.

Directions

Step 1: Make the crust dough

Preheat the oven to 350°F. In a large bowl, use a hand mixer or stand mixer to cream the butter and confectioners’ sugar until the mixture is light and fluffy, five to seven minutes. Beat in the lime zest.

In a separate bowl, whisk together the all-purpose flour and salt. Gradually add the flour mixture to the creamed mixture and mix well.

Editor’s Tip: Scrape down the sides and bottom of the bowl well to ensure everything is evenly incorporated.

Step 2: Par-bake the crust

Press the crust dough into a greased 13×9-inch baking dish. Pop the crust into the oven and bake just until the edges are lightly browned, 13 to 15 minutes.

Editor’s Tip: Use the bottom of a measuring cup to press the dough down and create an even layer.

Step 3: Prep the filling

In another large bowl, beat the eggs and sugar together with a hand mixer or stand mixer until combined. In a separate small bowl, whisk together the all-purpose flour and baking powder.

Gradually add the flour mixture to the egg mixture. Stir in the lemon juice and zest, then turn up the mixer and beat everything until frothy. Pour the filling over the hot crust.

Step 4: Bake the bars

Slide the pan back in the oven and bake the bars until they’re lightly golden brown, 20 to 25 minutes. Cool the lemon-lime bars at room temperature on a wire rack.

Step 5: Finish, cut and serve

Once the lemon-lime bars are completely cooled to room temperature, dust the top with confectioners’ sugar.

Cut the bars into squares and serve!

Recipe Variations

• Use a graham cracker crust: Classic lemon bars have a shortbread crust (it’s how Ina Garten makes her lemon bars!), but lots of people prefer a graham cracker crust instead. Feel free to bake these bars with a graham cracker crust or with other crumb crust ingredients like Ritz or Nilla wafers.
• Try other citruses: Switch up the citrus with oranges or grapefruit instead of lemons and/or limes.
• Add another topping: Not a fan of a confectioners’ sugar topping? Homemade whipped cream makes a wonderful replacement. Dress up the whipped cream with honey, spread it onto the cooled bars and finish with lime zest.
• Go gourmet: To make these lemon-lime squares a little fancier, swap in Meyer lemons and Key limes.

How to Store Lemon-Lime Bars

After the lemon-lime bars have cooled to room temperature, wrap them in their pan with storage wrap or transfer leftover slices to an airtight container. They can keep in the fridge for up to four days.

Can you make lemon-lime bars ahead of time?

Yes, you can make lemon-lime bars the day before serving. Store them, covered, in the fridge until you’re ready to serve, and then dust the top with the confectioners’ sugar just before serving.

Lemon-Lime Bar Tips

Can you use all lime or all lemon to make lemon-lime bars?

Yes, you can use all lime or all lemon to make lemon-lime squares. All lemons would make classic lemon bars. If you want to use all limes, I recommend our Key lime bars (regular limes can be used). These bars balance the sour filling with a delicious cream cheese layer underneath. Yum!

Can you double the filling?

Yes, you can double the filling if you prefer a thicker bar. Keep in mind, though, that they may take a little longer to bake, so allot for that extra time just in case.

Can you bake lemon-lime bars in a different-sized pan?

Yes, you can bake lemon-lime squares in a different-sized pan. Instead of a 13×9-inch pan, bake the lemon-lime bars in two 9-inch round pans or two 8-inch square pans.