Peel and finely chop the onion. Heat 10 g fat and fry the onion until transparent. Add peas, except some for garnishing. Deglaze with broth, bring to the boil, cover and leave to stand for about 15 minutes.
In the meantime heat milk, 15 g fat, salt and nutmeg. Add the flour and stir until the mixture separates from the bottom of the pot as a lump. Stir in egg. Add diced ham. Using 2 teaspoons dipped in cold water, cut off 12 dumplings and leave to stand in boiling water for about 10 minutes.
Mash the peas in the vegetable stock. Season to taste with salt, pepper and sugar. Stir the crème fraiche carefully into the soup. Serve pea soup with ham noodles and the rest of the peas and garnish with chives.