Key lime pie

Method

• step 1

  Heat the oven to 160C/fan 140C/gas 3. Crunch the biscuits into a food processor then whizz to crumbs or put in a plastic bag and bash to crumbs. Tip into a bowl and stir in the melted butter, then press the mixture into the base and sides of a 20cm loose-bottomed tart tin. Bake in the oven for 10 minutes, then cool completely.

• step 2

  To make the filling, put the egg yolks into a bowl. Use electric beaters to whisk for 2 minutes until paler. Add the condensed milk and whisk for another 4 minutes, then add the lime zest and juice and lemon juice and whisk again for 2-3 minutes until thickened. Pour into the pie case, then put back in the oven for 20 minutes. Cool then chill completely in the fridge. At this point cover with clingfilm and freeze until needed.

• step 3

  To finish, defrost the pie overnight if frozen. Whip the cream with the icing sugar until softly whipped. Dollop over the top of
  the pie, then finish with more lime zest.