Peel and dice the onions, cover with butter and cook for about 10 minutes. Pour in the chicken stock and bring to the boil.
Add the chicken breast fillets and parsley, season with plenty of salt and pepper. Cook the meat for about 15 minutes.
Melt the butter, add the flour and stir until the foam subsides. Whisk in the cream, simmer the sauce for 10 minutes.
Clean the mushrooms and cut into thin slices. Strain the chicken stock, press the residue through well. Add both to the sauce, bring to the boil. Season to taste with lemon juice and cayenne pepper.
Arrange the meat and pour the sauce over it. We also eat rice mixed with peas.