This is a very British version of the Key Lime Pie – an indulgent, creamy tart with tangy oranges and lemons.
For the crust:
250 g [8,8 oz] light digestive biscuit
100 g [3,5 oz] cornflake
85 g [3 oz] butter, melted
140 g [5 oz] caster sugar
For the filling:
1 large egg, plus 4 large egg yolks
397 g [14 oz] can light condensed milk
zest and juice 3 lemons
zest and juice 2 oranges
For the topping:
1,5 dl [5 fl oz] pot extra-thick double cream
100 g [3,5 oz] 0 % fat Greek yogurt
4 tbsp icing sugar
more lemon and orange zest, to decorate
 Heat oven to 180 C (355 F)/160 C (320 F) fan/gas 4. Sit a fluted 20 cm round loose-bottomed tin (about 5 cm deep, or a slightly shallower 22cm tin) on a baking sheet.
 Break the biscuits into a big bowl, or double-bag them in food bags, and bash to big crumbs with the end of a rolling pin or small saucepan. Add the cornflakes and bash a bit more to crumbs.
 Mix with the melted butter and sugar and press into the base and sides of the tin. Bake for 15 mins, then remove and reduce oven temperature to 160 C (320 F)/140 C (285 F) fan/gas 3.
 Whisk egg and yolks in a big bowl until pale and frothy. Whisk in the condensed milk, followed by the zests and juices. Pour in the tin and bake for 20 mins. Cool in the tin, then chill for at least 5 hrs, or overnight.
 Whip the cream, yogurt and icing sugar together. Dollop on the pie and scatter with zest to serve.