1/3 cup minced onions (I used a half cup, because I had a half-onion leftover from yesterday. no harm)
3 TB butter
3-4 packed chiffonade of spinach. 4 is better and I think 5 is better still. Also, one can use watercress or sorrel. Sorrel needs a chiffonade, watercress does not.
3TB flour
5 1/2 chicken stock
2 egg yolks
1/2 cup whipping cream
1-2 tb butter
If you are using boxed or canned chicken stock, but it on the fire now to get to boil. Cook onions slowly in butter, until tender and translucent but not brown. Stir in spinach and salt and cook about five minutes or so spinach is tender and wilted.
Sprinkle in flour and stir over a moderate heat for three minutes. Then, off heat, beat in boiling stock. simmer for five more minutes. Puree through food mill. If you don't have a food mill, blend then strain through sieve to remove fibrous bits.
Blend yolks and cream in the mixing bowl. Beat a cupful of hot soup into the mixing bowl by driblets. Gradually beat in the rest of soup in a thin stream. Return soup to saucepan and stir over moderate heat to poach eggs, but do not let simmer. Optional: you can add one or two more tablespoons of butter to enrich.
To be fancy you can put it in a tureen and top with a bit more spinach chiffonade, but we just ate it in cups.
It can be cold as well.. skip last bit of butter and chill.