a recipe for baked key lime pie

My sister made this for me and shared the recipe. She actually got the recipe from the Tesco magazine but apparently it orginally came from Lisa Faulkners book – Recipes from my Mother to my daughter
Its got quite a tart taste so would be good served with cream or icecream

Baked key Lime pie

Recipe

Biscuit base
4oz butter
80z digestive biscuit- crushed

Filling
3 large egg yolks
5 limes juiced plus zest from 4 of them
400g tin of condensed milk

Preheat the oven to 180 c
Melt the butter
Add the biscuit crumbs and mix well
Press the mixture into a 9 inch flan dish
Bake for about 10 minutes
To make the pie filling, whisk the egg yolks and most of the zest together until pale and thick. Keep some of the zest for decorating
Whisk in the condensed milk and then whisk in the lime juice
Pour the filling mixture onto the cooked biscuit base and return to the oven for 15 minute. Leave to cool in the dish and sprinkle with the remaining zest