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Easy Key Lime Pie

Creamy, smooth and packed with fresh lime flavour, this Key Lime Pie is the perfect make-ahead dessert. A crisp buttery digestive biscuit base is filled with a rich lime custard made from sweetened condensed milk, egg yolks and plenty of fresh lime juice, then baked until just set. After a few hours in the fridge it slices beautifully, making it ideal for summer gatherings, BBQs or simply as a refreshing dessert after dinner. Despite the name, you don't need authentic Key limes to make a fantastic Key Lime Pie. Regular supermarket limes work brilliantly and are much easier to find in the UK.

Published

Easy Key Lime Pie

At a glance

Prep
25m
Cook
15m – 18m
Chill
6h
Serves
8-12
Start Recipe Jump to Method

Ingredients

  • Biscuit Base

  • Filling

  • To Serve

Instructions

Prepare the Base

  1. Heat the oven to 190°C conventional / 170°C fan.

  2. Blitz the digestives into fine crumbs.

  3. Mix with the melted butter and caster sugar until evenly coated.

  4. Firmly press the mixture over the base and up the sides of a 23cm loose-bottom tart tin.

  5. Chill for 15 minutes.

  6. Bake for 10 minutes, then leave to cool while you prepare the filling.

Make the Filling

  1. Whisk the egg yolks for around 2 minutes until slightly lighter in colour.

  2. Add the condensed milk and whisk until smooth.

  3. Stir in the lime zest.

  4. Gradually whisk in the lime juice. The mixture will noticeably thicken but should still pour easily.

Bake

  1. Pour the filling into the cooled biscuit base.

  2. Bake for 15–18 minutes, until the edges are set but the centre still has a gentle wobble.

  3. Cool completely at room temperature.

  4. Refrigerate for at least 4 hours, preferably overnight.

Serve

  1. Top with whipped double cream, extra lime zest or thin slices of lime before serving.

Tips

  • Don't overbake. The pie continues to firm up as it cools.
  • Freshly squeezed lime juice gives the best flavour.
  • A loose-bottom tart tin makes removing and serving the pie much easier.
  • For the cleanest slices, dip a sharp knife in hot water and wipe it dry between cuts.

Substitutions

  • Swap Hobnobs for additional digestive biscuits if preferred.
  • Use salted butter for the base and omit the optional sugar.
  • Lemons can be used for a Lemon Pie variation, although the flavour will be noticeably different.
  • Bottled lime juice works in a pinch, but freshly squeezed juice gives the brightest flavour.
  • Serve with whipped cream, crème fraîche or vanilla ice cream.

Storage & Reheat

  • Store covered in the fridge for up to 3 days.
  • This pie is not suitable for freezing, as the filling can become grainy once thawed.

Serving Suggestions

  • Serve chilled with freshly whipped double cream.
  • Garnish with extra lime zest or thin lime slices.
  • Pair with fresh raspberries or strawberries for added colour and sweetness.
  • Enjoy with a cup of coffee or Earl Grey tea.
  • Perfect for BBQs, garden parties, picnics and summer celebrations.

Equipment

  • 23cm loose-bottom tart or quiche tin
  • Food processor (or rolling pin and freezer bag)
  • Mixing bowl
  • Whisk
  • Microplane or fine grater
  • Citrus juicer

FAQ

Can I use regular limes?
Yes. Traditional Key Lime Pie uses Key limes, but they are difficult to find in the UK. Regular limes produce an equally delicious pie with a bright, fresh citrus flavour.
Can I make it in advance?
Yes. In fact, it's even better made the day before serving, giving the filling plenty of time to fully set.
Why did my filling thicken before baking?
Fresh lime juice reacts with the proteins in the condensed milk, naturally thickening the filling before it even goes into the oven. This is completely normal.
Can I use a different biscuit?
Absolutely. Hobnobs make an excellent alternative, adding a slightly nuttier flavour and extra crunch to the base.