Preheat oven to 400° F.
Sauté onion and garlic in butter until golden. Set aside.
Put Brie and cream cheese in a bowl and microwave until soft. Mix in onion and garlic, sour cream, lemon juice, brown sugar and Worcestershire sauce; season to taste with salt and pepper.
Hollow out the middle of the loaf and fill with mixture. Wrap in foil and bake in oven until bubbly, approximately 20 to 30 minutes. Dust with paprika if desired. Serve hot with bread pieces or crackers.
Servings: 4