Desserts
America's Test Kitchen has perfected the key lime pie recipe—where the crust stays perfectly crisp, the filling delivers that signature tangy-sweet balance, and the meringue topping never cracks.
This isn’t just another dessert; it’s a foolproof method that delivers restaurant-quality results every time, with precise techniques that eliminate common pitfalls like soggy crusts or runny fillings.
The secret lies in the crust, which uses a high-fat shortening for flakiness and a cold press to prevent shrinking.
The filling achieves that perfect balance of zesty lime and sweetened condensed milk without curdling, while the meringue topping gets its structure from egg whites whipped to stiff peaks and baked just until golden.
Every step is designed to ensure your pie holds up through slicing and stays fresh for days.
What you’ll end up with is a pie that’s visually stunning—a vibrant yellow filling topped with a glossy meringue, all framed by a buttery, lattice-like crust. The first bite delivers that signature tangy-sweetness, with the meringue adding a delicate crunch that contrasts beautifully.
This isn’t just a dessert; it’s a showstopper that will have everyone asking for seconds.
Whether you’re baking for a holiday gathering or treating yourself to a classic, this recipe delivers professional-level results with techniques you can trust. Let’s get started—your perfect key lime pie awaits.
Ingredients for america's test kitchen key lime pie
High-fat crust, zesty filling, and glossy meringue—just 13 ingredients for restaurant-quality key lime pie.
| Ingredient | Amount | Notes |
|---|---|---|
| All-Purpose Flour 🌾 | 1 ½ cups | Sifted for light texture |
| Unsalted Butter 🧈 | ¾ cup | Cold, cubed, for flaky crust |
| High-Fat Shortening 🧈 | ½ cup | Crisco or similar brand |
| Diamond Crystal Kosher Salt 🧂 | ½ tsp | Fine grain preferred |
| Ice Water 💧 | ¼ cup | For dough consistency |
| Fresh Key Lime Juice 🍋 | 1 ½ cups | About 12-15 limes |
| Sweetened Condensed Milk 🥛 | 1 can (14 oz) | Unopened for best quality |
| Granulated Sugar 🍚 | 1 cup | White sugar preferred |
| Large Eggs 🥚 | 2 whole | Room temperature |
| Large Egg Whites 🥚 | 5 whole | Room temperature, pasteurized |
| Granulated Sugar 🍚 | 1 cup | For meringue topping |
| Diamond Crystal Kosher Salt 🧂 | ¼ tsp | For meringue stability |
| Fresh Key Lime Zest 🍋 | 1 tbsp | Fine, for garnish |
The crust starts with high-fat shortening—Crisco is the gold standard here—because it delivers that buttery, flaky texture without turning greasy. Unsalted butter is essential too, but keep it cold when mixing. I grab mine from Whole Foods for the best quality, but any reputable grocery store will have it. The flour? King Arthur or Bob's Red Mill are my go-tos—they're sifted and consistent. Never skip sifting; it's the difference between a good crust and a great one. For the key limes, Mexican limes (if you can find them) have more juice than Persian ones, but use what's available—just make sure they're bright green and firm.
No key limes? Persian limes or even regular limes work in a pinch, but you'll need about 20-25 to match the juice yield. The condensed milk must be unopened for the best texture—once opened, it thickens and loses its silky quality. For the meringue, pasteurized egg whites are a must if you're worried about safety, but regular eggs work fine if you're confident in their freshness. The sugar for the meringue should be superfine if you can find it—it dissolves faster and gives a smoother texture. Trader Joe's sells it pre-made, which saves time. The zest? Only the outer layer—don't get into the bitter white pith.
The crust dough can be made 2 days ahead and stored in the fridge—wrap it tightly to prevent drying. The filling keeps for 3 days in the fridge, but the meringue topping is best baked fresh. Once assembled, the pie stays fresh for 4 days in the fridge, but the meringue will darken slightly. For serving, garnish with extra zest right before cutting—it adds that pop of color and freshness. The lattice crust? Save that for another day; this pie deserves its full glory.
Why You'll Love This Recipe
- No-Fuss Crust: I swear by this crust—just flour, butter, shortening, and ice water. Mix it, press it, bake it. No rolling pins, no stress, and it’s always perfect.
- Tart Perfection: That key lime filling? Bright, creamy, and just sweet enough. The graham cracker crust holds up, the meringue stays crisp, and the tang cuts through every bite.
- Party Ready: Hosting a brunch? Bringing dessert to a potluck? This pie travels well, looks impressive, and disappears fast. (Between us, I’ve made it for weddings and it still gets raves.)
- Budget-Friendly Luxury: Shortening in the crust? Yes, it’s a splurge, but it’s worth it—flaky, buttery, and cheaper than store-bought. Leftovers? They’re rare, but if they happen, they taste just as good the next day.
Step-by-step instructions for america's test kitchen key lime pie
This foolproof method delivers the perfect balance of zesty tartness and creamy texture every time.
Prepare the Perfect Crust
In a large bowl, combine the 1.5 cups all-purpose flour and 0.5 tsp diamond crystal kosher salt. Cut in the 0.75 cup cold unsalted butter and 0.5 cup high-fat shortening using a pastry cutter or your fingers until the mixture resembles coarse crumbs with pea-sized butter pieces. Gradually add the 0.25 cup ice water, mixing just until the dough comes together.
Turn the dough onto a lightly floured surface and knead gently for 30 seconds until smooth. Wrap in plastic and chill for 30 minutes—this resting period is crucial for a flaky crust. Roll out the chilled dough to fit a 9-inch pie dish, then transfer it carefully. Trim and crimp the edges, creating a decorative border. Pre-bake the crust at 375°F for 15 minutes until lightly golden, then let it cool slightly before filling.
Make the Zesty Key Lime Filling
In a medium saucepan, whisk together the 1.5 cups fresh key lime juice, 1 cup granulated sugar, 1 can (14 oz) sweetened condensed milk, and 2 whole large eggs (room temperature). Cook over medium heat, stirring constantly, until the mixture thickens to 170°F on an instant-read thermometer—about 8-10 minutes. The filling should coat the back of a spoon and leave a slight trail when dragged through it.
Immediately pour the hot filling into the pre-baked crust. The heat helps set the custard quickly, preventing a watery center. Sprinkle the 1 tbsp fresh key lime zest evenly over the top for extra brightness. Let the pie cool to room temperature before refrigerating for at least 4 hours or overnight—this ensures clean slices and proper setting.
Create the Stable Meringue Topping
In a clean, grease-free bowl, beat the 5 whole large egg whites with the 0.25 tsp diamond crystal kosher salt on low speed until foamy. Gradually add the 1 cup granulated sugar, beating on medium-high until soft peaks form. Increase the speed to high and beat until the meringue is glossy and holds stiff peaks—about 3-5 minutes. The meringue should be thick enough to hold its shape when the bowl is tilted.
Spread the meringue evenly over the chilled filling, sealing it completely to the crust edges. Use the back of a spoon to smooth the surface. Bake at 325°F for 15-18 minutes until the meringue is golden brown. The center should spring back when touched lightly. Let the pie cool completely before slicing—this prevents the filling from oozing out.
Chill and Serve for Perfect Texture
Once completely cooled, refrigerate the pie for at least 4 hours or up to 24 hours. This chilling time is essential for the filling to fully set and the flavors to meld. When ready to serve, run a knife around the edges to loosen it from the dish. Slice into 8 equal wedges—each piece should have a vibrant green filling with a glossy meringue crown.
Serve at room temperature for the best texture contrast: the cool, creamy filling against the room-temperature meringue. Garnish with an extra sprinkle of key lime zest for a pop of color and aroma. The pie will keep well in the refrigerator for up to 3 days, though it's best enjoyed fresh when the flavors are at their peak.
Pro Tips For Making America'S Test Kitchen Key Lime Pie
- Chill the Dough Properly: The ATK crust recipe relies on cold butter and shortening for flakiness, but I learned this the hard way—don’t just toss it in the fridge for 30 minutes. Wrap it tightly in plastic and refrigerate for at least 2 hours (or overnight). The longer it rests, the less it shrinks when baking, and the more distinct those buttery layers become.
- Cut the Butter Cold: This isn’t just about softening—it’s about precision. Use a bench scraper or your fingers (fresh from the freezer) to cut the cold butter into the flour mixture in the exact pea-sized pieces the recipe specifies. Any larger, and you’ll end up with greasy pockets instead of flaky layers. I used to eyeball it, but measuring by volume (or using a scale for grams) guarantees consistency every time.
- Skip the Overmixing: The dough for this crust is supposed to look shaggy. Once you’ve mixed in the ice water, resist the urge to keep stirring—especially if it seems dry. Overworking it develops gluten, which makes the crust tough instead of tender. Two or three quick folds with a fork or spatula is all it takes. Trust the recipe: the dough will come together.
- Press It Evenly: The ATK crust relies on an even, thin layer to bake perfectly. Don’t press it into the pan with your fingers—use a glass or the bottom of a measuring cup to gently press it into place. This ensures an even thickness and prevents the edges from puffing up while the center stays flat. A quick spin of the pan helps distribute the dough evenly, too.
Dietary considerations for this recipe
Gluten-Free Adaptation
Replace the all-purpose flour in the crust with a 1:1 gluten-free flour blend like King Arthur Measure for Measure or Bob’s Red Mill 1-to-1. These blends mimic the structure of traditional flour, ensuring your crust stays flaky and sturdy.
For extra stability, add 1 tablespoon of xanthan gum to the dry ingredients—it mimics gluten’s binding properties. Chill the dough for an additional 10 minutes before rolling to prevent cracking. 🌾
Dairy-Free Options
The filling can easily go dairy-free by swapping sweetened condensed milk for coconut condensed milk (found in Asian markets or online). For the meringue, use aquafaba (chickpea brine) instead of egg whites—whip ½ cup aquafaba with 1 teaspoon cream of tartar and 1 cup sugar until stiff peaks form.
This vegan meringue holds just as well when baked. 🥥
Lower Sugar Version
Reduce the granulated sugar in the filling by ¼ cup and use monk fruit sweetener (like Lakanto) to maintain sweetness without spiking blood sugar. For the meringue, cut the sugar to ½ cup and add 1 teaspoon vanilla extract to enhance flavor.
The pie will still be sweet but with a lighter touch—perfect for those watching their sugar intake. 🍯
Nut-Free Caution
This recipe is naturally nut-free, but always double-check labels on sweetened condensed milk (some brands process in nut facilities) and gluten-free flour blends (which may contain cross-contamination warnings).
If you’re highly sensitive, opt for certified nut-free brands like Annie’s for the flour and Goya for the condensed milk. Safety first! 🛡️
Egg-Free Substitutes
For the filling, replace the 2 whole eggs with 2 tablespoons of cornstarch mixed with 2 tablespoons of water—this thickens the custard without eggs. For the meringue, use vegan aquafaba (as mentioned above) or a store-bought egg-free meringue powder like Daisy brand.
The texture will be slightly different but still delicious. 🥚
Allergen-Friendly Tips
If you’re accommodating multiple allergies, prepare the crust, filling, and meringue separately in a dedicated kitchen (or thoroughly clean surfaces between components). Use separate utensils for each stage to avoid cross-contamination.
Label each component clearly if serving to guests with dietary restrictions. A little extra care goes a long way! 💡
Nutrition facts
Frequently asked questions
Why does America's Test Kitchen recommend pre-baking the crust?
Pre-baking prevents a soggy bottom by removing moisture before adding the filling. The 15-minute bake at 375°F creates a sturdy base that holds up to the tangy lime custard. This step is especially critical for key lime pies, where the high acidity can weaken an unbaked crust.
Can I substitute Persian limes for key limes?
Yes, but you'll need about 20-25 Persian limes to match the juice yield of 12-15 key limes. Persian limes have less juice and more seeds. For best results, strain through a fine-mesh sieve to remove pulp and seeds. The flavor will be slightly milder but still delicious.
How do I fix weepy meringue after baking?
Weepy meringue happens when humidity interferes with setting. To prevent it, bake at 325°F with the oven door slightly open for 10 minutes before adding the pie. For existing weeping, chill the pie 24 hours to firm up the filling, then rebake at 300°F for 5-10 minutes to crisp the meringue.
What's the secret to a crack-free meringue?
Use a grease-free bowl and beat egg whites to stiff peaks with superfine sugar (or pulse regular sugar in a food processor). Spread meringue immediately after whipping and seal it to the crust edges. Bake at 325°F for 15-18 minutes—overbaking causes cracks. A damp pastry brush can smooth minor imperfections after baking.
Can I make this pie ahead of time?
Assemble the pie (without meringue) up to 2 days ahead and refrigerate. Add meringue 4 hours before serving to prevent sogginess. For best flavor, let it sit at room temperature for 30 minutes before slicing—this enhances the texture contrast between filling and meringue.