Melt butter in a heavy 4 quart saucepan over medium heat. Stir in flour to make a roux. Slowly add milk until it is well blended. Stirring constantly, add cheese and cook until mixture thickens. While reducing heat, add sherry, cream and parsley. When mixture is thoroughly heated, add crab meat, stirring gently to keep lumps intact.
Serve immediately in warmed bowls---garnish with chopped parsley. Serves 6.