Cook onion and garlic in butter for 8-10 minutes. Remove from heat and set aside. Place brie and cream cheese in microwave for 2 minutes. Whisk in sour cream, brown sugar, lemon juice, worchestershire sauce, salt, papper, and onion mixture. Hollow out bread bowl and place mixture inside. Replace the top and wrap in foil. Bake at 400F for 1 hour.