5: Beat on maximum speed for about 5 minutes until the yolks plump up a little in volume.
6: Reduce the beater speed slightly and slowly pour in 400 g sweetened condensed milk.
7: Reduce the beater speed further and slowly pour in the lime juice and zest.
8: Continue beating for a few more minutes until the mixture is fairly light.
9: Pour this filling into the tart case.
10: Cook for 10-15 minutes, just until the filling sets (check this by shaking the dish gently from side to side).
11: Leave to cool, then cover with stretch plastic film and refrigerate for at least 2 hours.
12: Just before serving, cover the top with rosettes of Chantilly (whipped cream).
13: Your Key lime pie is ready.
14: You can replace if you prefer, like Jeremy, Chantilly cream by a meringue French or Italian, so in that case brown the top like in a pear and lime meringue pie.
Remarks
This recipe is very well known in the USA and is typical of the South. There are many different variations: with meringue topping instead of cream, crushed biscuits and butter instead of pastry, etc. You can find mediocre versions all over Florida. These are ususally over-sweet, artificially flavoured and green coloured. Now, a good Key lime pie is not green!