Meatball Parmesan Burgers for #SundaySupper | Food Stuff

Ingredients

• 6 ciabatta rolls (or twelve "slider" size portobella mushrooms, stems and gills removed, rubbed with about a teaspoon of olive oil and sprinkled with a bit of kosher salt)
• 2 Tablespoons minced fresh parsley
• 1 clove garlic, minced or crushed
• 2 pounds ground beef
• ½ teaspoon kosher salt
• 6 slices mozzarella cheese
• ½ cup parmesan cheese
• ¼ teaspoon pepper
• portobellos, remove stem and gills - 450 for 10 minutes with a teaspoon or two of oil
• sliced roma tomatoes
• romaine lettuce
• about 6 Tablespoons tomato sauce, plus additional for serving, if desired