Bring skillet to medium high heat. Add ground beef and sear on each side for one minute.
Add onions and garlic and use spatula to start breaking up ground beef into crumbles. Stir frequently.
Ensure that you have not over-crowded pan — a crowded pan will cause “steaming” not the desired browning.
In last two minutes of cooking, stir in salt and Italian seasonings, mixing in well. Beef will be done when there is no longer any pink — approximately 6 to 10 minutes.
Drain off excess liquid and garnish with chopped parsley if desired.
To make peppers, slice tops of top 1/4 of pepper like a hat. Scrape out pith and seeds, discard. Set peppers in shallow dish with a bit of water and microwave for approximately 2 minutes until slightly softened, but not soggy and still keep shape.
Stuff each pepper with about 1 ounce each of spinach, 2 tablespoons chopped mushrooms, 1 ounce ricotta cheese and 3.5 ounces of cooked beef.
Place peppers on pan pour tomato sauce across tops of all. Sprinkle with mozzarella cheese. Place under broiler, watching carefully, until cheese is bubbling and beginning to brown.