1.Heat butter in pan, add finely chopped onion, thyme, bay leaf and finely chopped bacon. Saute slowly until very tender but not brown. Add cleaned livers, which have been soaked in salted water for 1 hour, then drained; simmer 7 minutes or until cooked.
2.Put cooked mixture and butter from pan into blender. Add brandy, port, sherry, salt, pepper, cream and finely chopped mushrooms to pan. Stir to combine, bring to boil, simmer gently uncovered until sauce has reduced by half. Pour sauce into blender, blend both together until smooth.
3.Push mixture through coarse sieve. Place in individual dishes. Refrigerate until firm.
4.Put extra butter in saucepan, melt over gentle heat until white sediment comes to top; skim off white sediment only. Place a bay leaf on top of each pate, pour the clarified butter over to cover top of pate; refrigerate until set.