Here's my old recipe - haven't made any for ages, though:
5 egg yolk
vanilla to taste (teaspoon of extract should do)
100 g sugar (caster or icing)
1/8 l cream (this is a German recipe, so it would have been whipping cream, half way between single and double)
3/8 l brandy
... and a lot of stirring.
Don't know about keeping qualities - ours never kept for long!
You can use evaporated/condensed milk instead of fresh, cream; might make it keep for longer.