American Cuisine
Key Lime Pie
By Dana Whitfield
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Key lime pie is the official pie of Florida, and its story is tangled up with the Keys, the chain of islands where small, aromatic Key limes grew and where fresh milk was scarce before refrigeration reached the region. Cooks leaned on canned sweetened condensed milk, and the magic of the pie is chemistry as much as flavor: the acid in the lime juice thickens the condensed milk into a silky custard with very little cooking, a technique that predates widespread home ovens in the area. Authentic Key lime juice is more tart and floral than the larger Persian limes found in most supermarkets, which is why the filling tastes brighter than a standard lime curd. The sour cream in this version softens the sharp edge and adds a faint tang reminiscent of cheesecake. A brief bake sets the eggless-style filling just enough to slice cleanly. This is a warm-weather dessert at heart, the kind of make-ahead pie that suits a summer dinner party or a holiday cookout because it has to chill for hours anyway. A cloud of whipped cream and a dusting of zest finish it the classic way.
Ingredients
Serves 8Instructions
- 1
Preheat oven to 350°F (175°C). In a medium bowl, mix graham cracker crumbs, sugar, and melted butter.
- 2
Press the mixture firmly into the bottom and up the sides of a 9-inch pie dish. Bake for 10 minutes until lightly browned. Cool on a wire rack.
- 3
In a large bowl, whisk together the sweetened condensed milk, sour cream, key lime juice, and lime zest until smooth and slightly thickened.
- 4
Pour the filling into the cooled crust. Bake for another 15 minutes, or until the filling is set but slightly jiggly in the center.
- 5
Remove from oven and let cool to room temperature. Refrigerate for at least 3 hours or overnight to fully set.
- 6
Top with whipped cream and extra lime zest before slicing and serving.
Chef's Tips
- ✦ Roll the limes firmly on the counter before juicing and zest them before you cut, since extracting fragrant oil from the peel is far easier when the fruit is whole.
- ✦ Bake the filling only until the edges are set and the center still jiggles slightly; residual heat finishes it as it cools and prevents a cracked, overcooked surface.
- ✦ Press the crumb crust with the flat bottom of a measuring cup to pack it evenly and tightly, which keeps slices from crumbling when served.
- ✦ Chill the pie for the full three hours, or ideally overnight, because the filling needs time to firm up completely before it will cut into clean wedges.
- ✦ Add the whipped cream only just before serving so it stays fluffy; topping it too early lets the cream weep and slide on the chilled filling.
Ingredient Substitutions
-
key lime juice → regular Persian lime juice
Use the same 3/4 cup. Persian limes are milder and less floral, so add an extra teaspoon of zest to boost aroma.
-
graham cracker crumbs → digestive biscuit or gingersnap crumbs
Use the same 1 1/2 cups. Gingersnaps add warm spice; digestives are the closest UK equivalent to graham crackers.
-
sour cream → plain full-fat Greek yogurt
Swap one-for-one at 1/2 cup. Yogurt is slightly tangier and looser, but the lime acid still sets the filling.
-
unsalted butter → salted butter or coconut oil
If using salted butter, skip any added salt. Melted coconut oil keeps the crust dairy-free but sets firmer when chilled.
-
sweetened condensed milk → dairy-free sweetened condensed coconut milk
Use two 11-14 oz cans to keep the volume the same; the filling will set a touch softer and carry a light coconut note.
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Frequently Asked Questions
Can I make key lime pie ahead of time? ▼
Key lime pie is an ideal make-ahead dessert. Bake and chill it up to two days in advance, keeping it covered in the refrigerator, and add the whipped cream topping just before serving so it stays light and fresh.
How long does key lime pie keep, and how should I store it? ▼
Store the pie loosely covered in the refrigerator for up to three days. Because it contains dairy and an eggless custard, keep it chilled at all times and discard any pie left at room temperature for more than two hours.
Can I freeze key lime pie? ▼
Yes. Freeze the un-topped pie wrapped tightly for up to one month. Thaw it in the refrigerator for several hours before serving, or eat it semi-frozen for an ice-cream-like texture, then add fresh whipped cream.
What can I use instead of key limes? ▼
Regular Persian limes work in the same 3/4 cup quantity; the flavor is a little milder and less floral, so add extra zest. Avoid bottled juice with preservatives if you can, as fresh juice gives a cleaner, brighter taste.
Why is my filling runny instead of sliceable? ▼
A runny filling usually means too little acid or not enough chilling time. Make sure you use the full 3/4 cup of lime juice so the acid can thicken the condensed milk, and refrigerate the pie at least three hours, preferably overnight, before slicing.
