Preheat the oven to moderately slow, 160°C (140°C fan-forced).
Bring the milk almost to the boil in a medium saucepan. Remove from heat.
Whisk together eggs, egg yolk, sugar and vanilla essence to taste in a bowl until just combined (do not aerate).
Gradually whisk the hot milk mixture into the egg mixture. Strain into a 1-litre (4-cup) capacity shallow ovenproof dish (or pie plate). Sprinkle with nutmeg.
Place dish inside a larger baking dish, Carefully pour boiling water into baking dish to come halfway up the sides of the custard dish. Bake for about 45 minutes or until custard just wobbles in the centre or when a small sharp knife inserted in the centre of custard comes out clean.