Easy Key Lime Bars Recipe

These are the bars you bring to a cookout and suddenly everyone turns into that friend who “doesn’t even like dessert” but somehow demolishes two. Tart key lime custard on a buttery graham crust, chilled until it slices like a dream. I love them because they feel fancy and sunshiny but they take, like, 20 minutes of actual effort and one bowl for the filling. It’s the vibe of a Florida vacation without the airport.

My little family is completely unhinged around these. My husband pretends he’s “just trimming the edges” and then leaves suspiciously even bars. The kid calls them “lime cheesecake squares,” which is not technically correct, but honestly? I get it. We started making them after a winter trip where I panic-bought a bag of key limes the size of marbles and spent an hour zesting with a microplane and a bad attitude. Worth it. Now I keep a bottle of key lime juice in the pantry so I can make these on a Tuesday when the week feels too long and we need a bright, tangy reset.

Why You’ll Love This Easy Key Lime Bars Recipe

– The filling is literally whisk-whisk-done. No stand mixer, no drama.
– That tart-sweet balance hits like sunshine. It’s zippy without puckering your whole face.
– Sturdy bars you can actually slice clean. I see you, bake sale people.
– Make-ahead magic: they taste even better the next day after a long chill.
– Uses one 14-oz can of sweetened condensed milk—no half-cans haunting your fridge.

How to Make It

Okay, first, preheat the oven to 350°F because the crust needs a quick bake to get snappy. Line an 8×8-inch pan with parchment, but leave little “handles” so you can lift the bars out later without doing a wrestling match. For the crust: mix 1 1/2 cups graham cracker crumbs with 3 tablespoons sugar, a pinch of salt, and 6 tablespoons melted butter. It should feel like damp sand that holds when you squeeze it. Press it into the pan—really press, corners too—then bake 8–10 minutes until fragrant.

While the crust takes its little spa moment, whisk the filling: 4 large egg yolks with 1 tablespoon finely grated lime zest (key lime if you’ve got it). Whisk for a minute to wake it up and turn the yolks a little pale. Now add one 14-oz can sweetened condensed milk and 2 tablespoons sour cream (optional but it makes it lush). Whisk smooth. Last, pour in 1/2 cup key lime juice and whisk just until it thickens slightly. Don’t overdo it—once the acid hits, it sets up fast.

Pour over the warm crust, give the pan a gentle shimmy, and bake 15–18 minutes. You want tiny bubbles around the edges and a center that still has a soft jiggle. That jiggle is your friend. Cool to room temp, then chill at least 3 hours (overnight if you can stand the wait). Slice into 16 squares, wipe the knife between cuts like a pro, and shower with a little extra zest or a dollop of whipped cream if you’re feeling extra.

Ingredient Notes

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– Key lime juice: Fresh is bright and floral, bottled works great too (Nellie & Joe’s is my pantry hero). Regular Persian limes are fine—just a touch less sharp.
– Sweetened condensed milk: The non-negotiable. Don’t swap for evaporated milk—it’s not sweet, not thick, and nope.
– Egg yolks: Yolks make the filling custardy and rich. Save the whites for breakfast egg bites or a tiny pavlova if you’re living your best life.
– Graham crackers: Classic. If you only have Biscoff or vanilla wafers, go for it—just watch the sweetness.
– Butter: Salted or unsalted; add a pinch of salt either way so the crust doesn’t taste flat.
– Lime zest: Don’t skip—this is where the real lime flavor lives. Zest first, then juice. Learn from my sticky-handed mistakes.
– Sour cream: Optional, 1–2 tablespoons. Adds body and tames sharpness. Skip if you want max pucker.
– Sugar (for crust): Keeps the crumbs sticking together. I’ve used coconut sugar in a pinch; slightly darker flavor but still good.

Recipe Steps

1. Preheat oven to 350°F and line an 8×8-inch pan with parchment, leaving overhang.
2. Stir 1 1/2 cups graham crumbs, 3 tbsp sugar, pinch salt, and 6 tbsp melted butter until sandy.
3. Press crumbs firmly into pan and bake 8–10 minutes until fragrant; cool 5 minutes.
4. Whisk 4 egg yolks with 1 tbsp lime zest for 1 minute; whisk in 1 can (14 oz) sweetened condensed milk and 2 tbsp sour cream.
5. Pour in 1/2 cup key lime juice; whisk just until slightly thickened, then pour over warm crust.
6. Bake 15–18 minutes until edges are set and center jiggles; cool, chill 3+ hours, slice into 16 bars.

What to Serve It With

– Lightly sweetened whipped cream and extra lime zest curls
– Fresh berries (strawberries and raspberries are perfect)
– Icy cold brew or a tiny espresso shot for contrast
– Toasted coconut flakes if you want vacation energy
– A salty pretzel twist on the side because sweet + salty = yes

Tips & Mistakes

– Don’t overbake. If the center doesn’t wiggle, you’ve gone too far. Overbaked = rubbery.
– Zest first, then juice. Zesting a deflated lime is a workout I don’t recommend.
– Line the pan. You’ll thank yourself when those clean-edged squares lift right out.
– Use room-temp yolks for a smoother fill—cold yolks can get streaky.
– Bottled key lime juice is fine, but taste your batter. If it’s too sharp, add another tablespoon of sweetened condensed milk or a teaspoon of sugar.

Storage Tips

Slide leftovers into an airtight container and keep them in the fridge up to 5 days. They’re best cold—firm, creamy, no ooze. If you “accidentally” eat one for breakfast with coffee, I’m not judging. To freeze, wrap the slab or individual bars tight and freeze up to 2 months; thaw in the fridge so the crust stays snappy.

Variations and Substitutions

– Pretzel crust: Swap half the graham crumbs for crushed pretzels. Salty-tangy magic.
– Lemon bars but make it creamy: Use lemon juice and zest instead of lime. Slightly sweeter, still bright.
– Coconut twist: Add 1/2 cup finely shredded coconut to the crust and a splash of coconut extract to the filling.
– Gluten-free: Use GF graham crackers. Works perfectly—just press the crust firmly.
– Sweetness tweaks: You can cut the crust sugar to 2 tbsp. I don’t recommend honey here; it makes the crust sticky and soft.
– No sour cream: Totally fine—just a slightly sharper, lighter filling.
– 9×13 pan: Double everything and bake 18–22 minutes.

Frequently Asked Questions

Easy Key Lime Bars Recipe

Creamy, tangy key lime bars on a buttery graham cracker crust. Simple to make with pantry staples and fresh lime juice for a bright, refreshing treat.

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Prep Time: 20 minutes minutes

Cook Time: 25 minutes minutes

Total Time: 45 minutes minutes

Servings: 16

Calories: 120kcal

Ingredients

 

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Main Ingredients

• ▢ 1.5 cup graham cracker crumbs
• ▢ 0.25 cup granulated sugar for crust
• ▢ 0.5 cup unsalted butter melted
• ▢ 0.125 teaspoon fine sea salt
• ▢ 4 large egg yolks room temperature
• ▢ 28 ounce sweetened condensed milk two 14-ounce cans
• ▢ 0.25 cup sour cream room temperature
• ▢ 0.75 cup fresh key lime juice or regular lime juice
• ▢ 1 tablespoon lime zest finely grated
• ▢ 1 cup heavy whipping cream cold, for topping
• ▢ 2 tablespoon powdered sugar for topping
• ▢ 0.5 teaspoon vanilla extract optional, for topping
• ▢ 0.5 teaspoon lime zest for garnish

Instructions

Preparation Steps

• Preheat oven to 350°F. Line an 8x8 inch baking pan with parchment, leaving overhang for easy lifting.
• Make the crust: In a bowl, combine graham cracker crumbs, granulated sugar, and salt. Stir in melted butter until the mixture resembles damp sand.
• Press crust firmly and evenly into the prepared pan. Bake for 8 to 10 minutes until lightly golden. Let cool 5 minutes while you make the filling.
• Make the filling: Whisk egg yolks until slightly thickened and pale, about 1 minute. Whisk in sweetened condensed milk and sour cream until smooth. Fold in lime zest and whisk in lime juice until the mixture thickens slightly.
• Pour filling over the warm crust and smooth the top. Tap the pan gently to release air bubbles.
• Bake for 12 to 15 minutes, until the edges are set and the center has a slight wobble. Do not overbake.
• Cool on a rack for 30 minutes, then refrigerate until fully chilled and set, at least 2 hours.
• Whipped topping: Beat cold heavy cream with powdered sugar and vanilla until soft peaks form.
• Lift bars from the pan using parchment, slice into 16 squares, and top with whipped cream and a sprinkle of lime zest.

Notes

For the brightest flavor, use freshly squeezed key lime juice. Regular Persian limes also work. Bars slice cleanest when well chilled. Store covered in the refrigerator for up to 4 days.