Key Lime Pie
A no-cook-custard pie set almost entirely by acid reacting with sweetened condensed milk.
Makes 1 9-inch pie · Prep 15 min · Bake 15 min
Ingredients
Crust
- 1 1/2 cups Graham cracker crumbs
- 6 tbsp Butter, melted
- 2 tbsp Granulated sugar
Filling
- 14 oz Sweetened condensed milk
- 4 Egg yolks
- 1/2 cup Lime juice — key lime if available
- 1 tbsp Lime zest
Topping
- 1 cup Heavy cream, cold
- 2 tbsp Granulated sugar
Instructions
Prep
- Heat the oven to 165°C (330°F).
Crust
- Mix the graham crumbs, melted butter, and sugar and press firmly into a 9-inch pie pan. Bake to set.
Filling
- Whisk the condensed milk and egg yolks together until smooth, then whisk in the lime juice and zest. (Tip: Watch it thicken as the acid hits the condensed milk — this reaction, not the oven, is doing most of the actual setting work.)
Bake
- Pour into the crust and bake until just set at the edges with a slight give in the centre. (Tip: This short bake is mainly for food safety, pasteurising the yolks, and a little extra firmness — it isn't carrying the whole structural load the way a fully heat-set custard would.)
Chill
- Cool completely, then chill until fully cold.
Topping
- If using, whip the cream and sugar to soft peaks and spread or pipe over the chilled pie before serving.
Tips
- Filling stayed thin: Uncommon, but possible if the lime juice wasn't acidic enough — bottled juice or juice from underripe limes can be milder than expected. Fresh, ripe lime juice consistently gives the best set.
- Real key limes vs. standard limes: Key limes are smaller, more aromatic, and noticeably more tart. Standard Persian limes make a perfectly good pie, just with a slightly milder, less distinctive flavour than the name technically implies.