In a kettle sauté chopped onion and sliced celery in butter until soft. Stir in flour.
Remove from heat and stir in milk, chicken broth, and chicken bouillon cube; mix well. Return to heat and simmer, stirring, until the soup thickens. Add diced Brie cheese and stir until melted. Transfer the soup to a food processor and blend until smooth. Add salt, pepper, and cayenne pepper. Heat through.Servings: 6