In a large saucepan cook mushrooms and onion in hot butter about 5 minutes or until tender. Stir in flour, pepper, and salt. Add vegetable broth all at once. Cook and stir until thickened and bubbly.
Stir in milk, brie, and tomatoes. Cook and stir about 7 minutes more or until brie is melted. Stir in crab meat and heat through. Serve in bowls topped with parsley and Romano cheese. Makes 4 main-dish servings or 8 appetizer servings.