Perfect Cast Iron Grilled Cheese - Challenge Dairy

Ingredients

• 2 Tablespoons Challenge Butter, softened
• mayonnaise
• 4 slices sourdough bread
• 2 slices sharp cheddar cheese, sliced ¼-inch thick
• 2 slices Swiss, gruyere, or pepper jack cheese, sliced ¼-inch thick
• ½ medium yellow onion, chopped and grilled (optional)
• ½ cup button mushroom, sliced and grilled (optional)
• 4 slices tomato, thinly sliced (optional)
• ham or turkey slices (optional)