Key Lime Pie

1. Heat the oven to 160C/fan 140C/gas 3. Whizz the biscuits to crumbs in a food processor (or put in a strong plastic bag and bash with a rolling pin). Mix with the melted butter and press into the base and up the sides of a 22cm loose-based tart tin. Bake in the oven for 10 minutes. Remove and cool.
   10 minutes
2. Put the egg yolks in a large bowl and whisk for a minute with electric beaters. Add the condensed milk and whisk for 3 minutes then add the zest and juice and whisk again for 3 minutes. Pour the filling into the cooled base then put back in the oven for 15 minutes. Cool then chill for at least 3 hours or overnight if you like.
   3 minutes3 minutes15 minutes3 hours
3. When you are ready to serve, carefully remove the pie from the tin and put on a serving plate. To decorate, softly whip together the cream and icing sugar. Dollop or pipe the cream onto the top of the pie and finish with extra lime zest.

Cooking notes

Baked goods are unforgiving with rounding — use weights rather than volumes whenever possible, and verify pan capacity if you scale up or down significantly.

For volume-to-weight conversions of any ingredient — flour, sugar, butter, salts — use the ingredient converter. To translate the recipe's oven temperature between °C, °F and gas mark, see the temperature converter.

When you scale this recipe up or down, remember that cooking time does not scale linearly. A doubled cake takes longer, but not twice as long; a doubled soup takes roughly twice as long. The cooking-time guide gives sensible starting estimates by dish geometry.