Mary Berry Key Lime Pie

I remember the first time I tasted Key Lime Pie. It wasn’t in Florida or anywhere remotely tropical — it was a rainy Tuesday in Devon, and my auntie Sheila had decided to “try something American.” She served it with a pot of over-brewed PG Tips, and honestly, it was divine. That sweet-sour creaminess against the buttery biscuit base — pure magic. Now every time I make Mary Berry’s version, it pulls me right back there: damp socks, retro china, and all.

This Mary Berry Key Lime Pie recipe is a little British twist on an American classic, made with digestive biscuits instead of graham crackers and topped with gently whipped cream. It’s wonderfully easy — no oven required — and deeply satisfying, especially on a warm day when you want something cool, creamy, and citrusy.

Ingredients List

For the crust:

• 150g digestive biscuits — classic British crunch, subtly sweet and toasty
• 65g unsalted butter — melted, to bind everything beautifully
• 25g demerara sugar — adds a gentle caramel note and a bit of sparkle

For the filling:

• Zest of 1 large lime — intensifies the lime flavour without overpowering it
• Juice of 4 large limes — tangy and bright, this is what gives the pie its signature zing
• 397g condensed milk — creamy, sweet, and helps the pie set without baking
• 450ml double cream — makes it lush and silky

No need for eggs, gelatine, or faffing with water baths — it sets all on its own like a little miracle.

How to Make It

1. Crush the biscuits
   Pop your digestives in a freezer bag and bash with a rolling pin. You want a fine, sandy texture. Therapeutic, really.
2. Make the crust
   Melt your butter in a saucepan (don’t let it brown), then stir in the sugar and crushed biscuits. Mix until it resembles wet sand.
3. Press and chill
   Tip the mixture into a 23cm loose-bottomed tart tin. Press it in firmly — I use the bottom of a glass — and get it up the sides. Chill for at least 30 minutes. Don’t skip this part; it’s what keeps your base together.
4. Mix the filling
   In a large bowl, combine the lime juice, zest, condensed milk, and 300ml of the double cream. Stir gently until it thickens. It’ll go from runny to creamy in under a minute — like magic. Don’t overdo it.
5. Fill the crust and chill
   Pour the mixture into your chilled crust. Smooth the top with a spatula and pop it back in the fridge for 2–3 hours, until set. I usually clean the kitchen and then forget I’ve made it.
6. Decorate
   Whip the remaining 150ml cream until soft peaks form. Pipe or spoon it on top, then sprinkle with extra lime zest. Looks lovely, tastes better.

Common Mistakes

Can I use regular limes?
Yes, and I usually do. Key limes are traditional, but regular limes work beautifully — just make sure they’re fresh and juicy.

Why is my filling runny?
You might have overmixed or not chilled it long enough. Let the fridge do its thing.

Do I really need to chill the base?
Absolutely. A warm base won’t hold its shape and will crumble when you slice it.

My whipped cream went gloopy. What happened?
It was overwhipped. Stop at soft peaks — you want it cloud-like, not butter-ish.

My crust came out uneven.
Join the club. Try using a straight-sided glass to press evenly next time.

Storage and Reheating Tips

• Fridge: Keep it in the fridge, covered, for up to 3 days. Best served chilled.
• Freezer: You can freeze it whole or in slices. Wrap tightly and freeze for up to 2 months. Defrost in the fridge overnight — the texture holds up well.
• Reheating: Don’t. It’s a chilled dessert — heating ruins the creaminess.

What to Serve With It

• Fresh raspberries or strawberries — They bring a nice sharp contrast.
• A pot of mint tea — The herbiness works surprisingly well with the citrus.
• Limoncello or a crisp glass of white wine — If you’re feeling fancy (or on holiday in your mind).

FAQ Section

Can I make this gluten-free?
Yes — just use gluten-free digestives or a GF biscuit of your choice. The filling is naturally gluten-free.

Is it safe to eat without baking?
Absolutely. No eggs involved. The acid in the lime sets the cream and condensed milk.

Can I make this ahead for a party?
Definitely. In fact, it’s better made the day before. The flavours mellow and the set holds stronger.

Can I use a different citrus?
You can, but lime is key here. Lemon makes it sweeter and orange is too mild. A combo of lime and lemon works in a pinch.

Try More Recipes:

• Mary Berry Guinness Cake
• Mary Berry Pineapple Upside Down Cake
• Mary Berry Butterscotch Tart