Finely chop the onion and brown it in butter in a saucepan. Add the flour and brown while stirring, then remove the pan from the heat. Deglaze with cold water while stirring with a whisk and bring to the boil. Add the vegetable stock, salt, cloves and bay leaves and cook the sauce for 15 minutes.
At the same time, cook the spaetzle.
Sauté the cleaned beans in a little butter, deglaze with a little water and simmer for about 5 minutes. Strain the sauce through a sieve to the beans and simmer for another 5 minutes. Season with balsamic vinegar and serve with the spaetzle.