Prepare your mushrooms by removing all dirt and particles with a damp paper towel. Remove stem from each; chop and set aside. Remove ribbings and throw away.

In a medium saucepan, brown sausage with diced onion until sausage is no longer pink. Add garlic and cook an additional 60-90 seconds. Transfer to a bowl and stir in salt, cream cheese, and chopped mushroom stems; set aside. Place broiler rack 2-4 inches from the hear source and preheat broiler.

Brush each mushroom with melted butter, season with salt, and broil stem side down for 2 1/2 minutes.

Remove from broiler, turn over caps, and fill with prepared filling. Sprinkle each mushroom with cheese followed by panko bread crumbs.

Return to broiler and broil 2-4 minutes until bubble and breadcrumbs are a golden brown.