For the soup, sweat the onions in butter, deglaze with wine and reduce a little (so that the alcohol evaporates). Pour in the broth, add cheese, garlic and sour cream, bring everything to the boil and simmer for another 10 minutes. Puree with a hand blender. Just before serving, stir in the whipped cream loosely.
For the dumplings mix all ingredients except the flour and let stand for about 1/4 hour and let steep. Then mix in the flour. Form small dumplings and let them simmer in gently simmering salted water for 10-15 minutes (duration depending on size, cut a test dumpling open to see whether they are already done).