Wash the chard well and separate the main bits of the stalks from the leaves. Cut off any ragged untidy ends of the stalk too.
Chop the stalks into small dice the same size as or slightly larger than your chopped onion (no bigger than your finger nail)
Heat the oil in a large frying pan and saute the onion and chard stalks over a medium heat for about 10 minutes, stirring occasionally to make sure they don't brown.
Then add the chard leaves which you've stacked, rolled and sliced into fine ribbons and cook for another five minutes - keep the leaves moving until they wilt down.
Add cream and the bouillon and the nutmeg and cook gently for another five minutes until the cream has started to thicken and is well incorporated into the chard and onion. Season with salt and black pepper to taste.
Serve with spaghetti or tagliatelle ( about 370 g dry weight for 4 people). Don't be tempted to swamp the pasta just a couple or 3 tablespoons of the sauce per person should do.