Cream of porcini soup

This looks like one of my mother's more recent recipes. Serves 4:

1 knob butter
1 finely chopped onion
500 g flat mushrooms (finely sliced)
50 g dried porcini (soaked)
4 bashed cloves garlic
1 glass white wine
1 l fresh chicken stock or tinned consommé diluted 50/50 with water
100 ml crème fraiche

Soak porcini in hot water until soft. Melt butter in large saucepan & add next 4 ingredients. Turn down heat & cover. Cook gently for 20 m. Add white wine & reduce by 1/2. Add stock & bring to boil. Simmer 10 m & add cream. Remove heat. Liquidise in small batches and return to clean pan. Season with salt and pepper.