Key Lime Bars Recipe (With Step-by-Step)

Prep Time:

25 mins

Cook Time:

20 mins

Total Time:

4 hrs 45 mins

Servings:

12 Servings

If you love the tart, tangy taste of Key lime pie, you'll adore these Key lime bars. Featuring a creamy condensed milk filling flavored with Key lime juice atop a buttery graham cracker crust, each bar has a mouthwatering contrast of flavors and textures.

The recipe is a riff on the famous Key lime pie from Joe's Stone Crab restaurant in Miami Beach. It's sure to be a standout option on your summer dessert table. Make it for pool parties, potlucks, casual patio get-togethers, or whenever you’re craving a cool sweet treat. Plus, since the dessert is in bar form, it's easy to enjoy—no forks or plates required.

How to Store Limes

Key limes, like other limes and other citrus fruits, can be stored at room temperature for two to three days. Be sure to keep the fruit out of direct sunlight and avoid overcrowding the fruit bowl. For longer storage, keep the limes in the refrigerator.

If you can't find Key limes, use regular fresh lime juice or even lemon juice for these bars.

Sweetened Condensed Milk vs. Evaporated Milk

One of the key ingredients in these bars is sweetened condensed milk. Thick and syrupy, it blends with the egg yolks to form a rich, creamy custard that sets up beautifully. It's also responsible for sweetening these bars without the need for additional sugar.

When shopping, be sure to buy sweetened condensed milk and not evaporated milk, which is much thinner and does not contain sugar. The two products are typically sold in similar size cans right next to one another but cannot be used interchangeably.

Directions

Ingredients for Key Lime Bars — Rachel Marek

Preheat oven and prepare crust:

Preheat oven to 350°F. Stir together crumbs, sugar, and butter in a small bowl.

Rachel Marek
Press crust into pan and bake:

Press evenly onto bottom of an 8-inch square glass or ceramic pan. Bake until dry and golden brown, about 10 minutes. Let cool in pan on a wire rack. Leave oven on.

Rachel Marek
Mix egg yolks and zest for filling:

Place egg yolks and zest in the bowl of an electric mixer fitted with the whisk attachment; beat on high speed until mixture is very thick, about 5 minutes.

Rachel Marek
Add condensed milk:

On medium speed, pour in condensed milk in a steady stream, scraping down sides of bowl. Beat on high speed until thick, about 3 minutes.

Rachel Marek
Add lime juice:

On low speed, add lime juice; mix until just combined.

Rachel Marek

Rachel Marek
Add filling to crust, bake, and chill:

Pour filling over crust; spread evenly. Bake until just set, about 10 minutes.

Rachel Marek

Rachel Marek
Cool, then chill:

Let cool completely on a wire rack. Chill at least 4 hours or overnight.

Rachel Marek
Prepare topping and serve:

Beat cream in a medium bowl until stiff peaks just form.

Rachel Marek
Cut into rectangles for serving:

Cut dessert into 1 1/2-by-2-inch rectangles. Garnish each with whipped cream and a slice of Key lime.

Rachel Marek

Key Lime Bar Crust Variations

Instead of graham crackers, use vanilla wafers or Biscoff cookies for the crust. You can also add warming spices to the crumbs for extra flavor. Delicious examples include cinnamon, nutmeg, allspice, or five-spice powder.

Other Toppings

While we love a dollop of whipped cream to finish these bars, there are other possible garnishes instead of or as well as the cream:

Lime zest
Dusting of powdered sugar
Shredded coconut

Storing Key-Lime Bars

Key-lime bars should be stored in the refrigerator. Wrapped in plastic, theywill keep for up to 3 days. They cannot be frozen.

Frequently Asked Questions

What is the difference between Key limes and regular limes?

The main difference between Key limes and regular limes is that Key limes are smaller and more acidic than regular limes. However, you can use regular lime juice in place of Key lime juice in most recipes. Just be sure to use freshly squeezed juice, not the bottled kind, which tends to be too tart.
Can I substitute lemon juice for Key lime juice?

Yes! You can substitute lemon juice for Key lime juice. The flavor of the finished dish will be different but it will work. Simply replace the Key lime juice with the same amount of fresh lemon juice. You can also use equal parts lime and lemon juice for a tasty twist.
Why do these bars need to chill for four hours?

These Key-lime bars need to chill for four hours to thoroughly set the filling—this is key to their firm yet creamy consistency. If served sooner than that, the filling may be too runny to slice properly. Like traditional Key lime pie, the flavor of these bars is much better when served cold.