In a large saucepan, melt 2 tablespoons butter and add the carrots, onions, parsley, bay leaf, and thyme. Cover the pan and cook the vegetables slowly until they are tender. Add the white wine and the shrimp and poach them for about 8 minutes.
Remove and reserve the shrimp.

When the shrimp are cool enough to handle, shell and de-vein twelve of them, reserving the shells.
Cut the meat into dice and reserve it.
Put the shells and the remaining whole shrimp through the food chopper and add the chopped mixture to the kettle with the mirepoix and poaching wine.
Stir in the flour. Add the chicken stock, bring the soup back to a boil, and simmer it for 20 minutes.
Strain it through a fine sieve and if it is too thick, add a little milk.
Strain it again through a thickness of cheesecloth. 

Just before serving, bring the soup back to a boil and add the cream and 2 tablespoons each of butter and brandy, sherry, or Madeira.
Garnish each serving with the reserved diced shrimp.