Bring the broth to the boil for the sauce. Knead the butter and flour and dissolve in the broth while stirring. Simmer over a low heat for 5 minutes. Pour in the cream and season the sauce with salt, pepper and lemon juice.
For the gnocchi, wash the potatoes, cook them until they are done, drain, peel them while still hot and press them through the potato press. Rinse off the wild garlic, shake dry and puree with the egg. Knead with flour, potatoes, a little salt and some freshly grated nutmeg to form a smooth dough (if it is still sticky, just add a little flour) and then let it rest for 30 minutes, covered.
Divide the dough into 6 portions and shape into finger-thick rolls on a floured work surface, cut each into 2 to 3 cm long pieces and shape them into balls, flatten them a little and make a pattern with a fork. Let the gnocchi simmer in portions in boiling, lightly salted water for 4 to 5 minutes. Once they float on top, take them out and keep warm.
Peel the onions, cut into rings and sauté in butter until translucent. Serve with wild garlic gnocchi and the cream sauce.