Peel onions; cut a thin slice from bottom of each one, forming a base for onions to stand on. Scoop out a shallow hole in top of each onion.
Place each onion on a 12-inch square of heavy-duty aluminum foil; wrap sides of each one, forming a basin for liquid. Allow some overhang of foil, leaving tops of onions exposed.
Stir together broth and next 3 ingredients; drizzle evenly over onions. Stir together seasoning blend, garlic salt, and lemon pepper. Sprinkle about 2 tablespoons of seasoning mixture over each onion. Top each with 1 tablespoon butter.
Press foil edges together; gently twist to seal. Place on a baking sheet.
Bake at 400° for 1 hour and 15 minutes. Gently unseal foil edges, leaving onions and liquid in foil cups. Top onions evenly with cheese.
Broil 5 1/2 inches from heat 1 to 2 minutes or until cheese melts. Serve immediately.
* Swiss cheese, Monterey Jack cheese with peppers, or fontina cheese may be substituted for Jarlsberg cheese.
Note: For testing purposes only, we used Morton Natures Seasons Seasoning Blend for seasoning blend.