It's an egg cooked slowly at a very precise temperature (from 60C to 65C) to achieve a high-impact result: a shimmering, silky orb of creamy egg white surrounding a rich, softly liquid egg yolk. Forget your three-minute egg; this can take anything up to 2 hours.

Where is it?

At Andrew McConnell's Cumulus Inc, weekend breakfasts are devoted to the famous 65/65 egg (65-gram eggs cooked for 65 minutes) served with grilled Lyonnaise sausage, braised beans and smoked hock. During the week, the egg is served with smoked sardines, grilled asparagus, tomato and sorrel on toast. At Prahran's Hobba Coffee & Kitchen, the perfectly cooked 63C eggs come with grilled asparagus, hazelnut crumbs and horseradish panna cotta; and at Canterbury's Maling Room, they're served with chorizo and roast tomatillo salsa, grilled corn, avocado and tomato. "We don't do a traditional poached egg at all any more," Maling Room manager Adam Howes says. "Although we do have to warn our customers when they order that the eggs are soft, as some people freak out."

Why do I care?

Because chefs from Britain's Heston Blumenthal to Spain's Andoni Luis Aduriz consider it ''the perfect egg''. Because it's very impressive served over hot-smoked salmon, grilled tuna, new-season asparagus or baked beans and sausages. Or just because it gives you more time to get the toast on and the coffee made.

Can I do it at home?

For precise results, you need an immersion circulator, the temperature-controlled water bath used by chefs. Failing that, you can still have fun experimenting with an instant-read cook's thermometer (about $6), a big pot, and a simmer pad, but it's a bit hit and miss.

Slow-cooked egg and jamon on toast

5 x 65g eggs, room temperature

1 garlic clove, roughly crushed

3 tbsp extra-virgin olive oil

4 thick slices sourdough bread

8 slices jamon or prosciutto

4 tbsp chervil or microcress

Sea salt and cracked black pepper

1. Heat water in a large saucepan or stockpot until a cook's thermometer reads 60C to 62C. Place a saucer on the bottom to stop the eggs from gathering on the base, where the temperature is highest.

2. Carefully add the eggs and cook for 50 minutes, keeping the temperature constant. Remove a ''test'' egg, crack in half, and slide on to a warm plate. The white should be soft, translucent and jelly-like, and the yolk still gently runny. If not yet cooked, give the others another 5 to 10 minutes.

3. To serve, stir the garlic into the olive oil. Grill the sourdough bread, brush with the garlicky olive oil, and top with folds of jamon and lots of chervil. Arrange egg on top, drizzle with remaining olive oil, scatter with sea salt and pepper and serve.

Recipe note on timing and temperature:
I tried everything from cooking the eggs for 1 minute per gram (for example, a 60-gram egg for 60 minutes) to varying the temperature from 60C to 64C. While the whites were beautifully translucent, the yolks went one stage past runny. Try it yourself, or master the traditional poached egg instead. Serves 4