Key lime pie

Ingredients

Crust

• 200 ggraham crackers or digestive biscuits
• 100 gbutter, melted
• 2 tbspsugar

Filling

• 400 gsweetened condensed milk
• 4egg yolks
• 150 mlkey lime juice
• zest of 4 key limes

To serve

• 300 mldouble cream, whipped
• lime zest

Directions

1. Key limes are smaller, yellower, more acidic and more floral than Persian limes, and they are what the pie is named for.
2. Bottled key lime juice is entirely acceptable and is what most Florida kitchens use, because juicing enough tiny limes by hand is genuinely tedious.
3. Crush the biscuits to fine crumbs and mix them with the melted butter and sugar.
4. Press the mixture firmly into a pie dish, up the sides, using the base of a glass.
5. Press it hard and compact it properly, or the crust crumbles when you cut the first slice.
6. Bake the crust at 175°C (345°F) for 10 minutes and let it cool.
7. Whisk the egg yolks with the lime zest for a couple of minutes until pale and slightly thickened.
8. Beat the zest with the yolks first. It releases the oils into the fat, which is where the aroma lives, and stirred in at the end it just sits there.
9. Whisk in the condensed milk, then add the lime juice and whisk until smooth.
10. The filling thickens visibly as the juice goes in. That is the acid setting the condensed milk, not a mistake, and it is the reason this pie exists at all.
11. It was invented before refrigeration was common in the Keys, when tinned condensed milk was the only milk available and the lime acid set it without cooking.
12. Pour the filling into the cooled crust.
13. Bake at 175°C (345°F) for 12 to 15 minutes, until the centre is just set with a slight wobble.
14. Take it out while it still wobbles. Baked until firm it cracks as it cools and turns rubbery.
15. Cool completely, then chill for at least 4 hours and preferably overnight.
16. Top with whipped cream and lime zest just before serving.
17. It is naturally pale yellow from the yolks and the key limes. A green key lime pie has had colouring added and is a giveaway.
18. It is the official pie of Florida and Key West restaurants take the question of meringue against whipped cream extremely seriously.

Technique

• Never green. Key lime juice is yellow and so is the pie.
• Some versions use meringue instead of whipped cream, which is the older restaurant style.
• Persian limes work and give a sharper, less floral pie.

Substitutions

• Bottled key lime juice, which is standard even in Florida.
• Digestive biscuits in place of graham crackers.

Variations

• With a meringue top, browned under the grill.
• Frozen, as a key lime ice box pie.
• With a pastry crust rather than crumb.

History

A Florida Keys dessert from the era before refrigeration, when canned condensed milk was the only milk on the islands.

Frequently asked questions

What is Key lime pie?

Key lime pie is a dessert from United States: tart custard of key lime and condensed milk in a graham crust. A Florida Keys dessert from the era before refrigeration, when canned condensed milk was the only milk on the islands.

How long does Key lime pie take to make?

Key lime pie takes 25 min plus 4 hr chilling of preparation and 25 min of cooking. The recipe makes 1 pie. It is rated easy to make.

What can I substitute in Key lime pie?

Yes, within limits. Bottled key lime juice, which is standard even in Florida. Digestive biscuits in place of graham crackers.

What is the most important thing to get right in Key lime pie?

It was invented before refrigeration was common in the Keys, when tinned condensed milk was the only milk available and the lime acid set it without cooking.