Preheat the oven to 400 degrees
Heat a medium size pan over medium heat. Once hot, add the ground beef and cook until no longer pink.
Once the beef is finished cooking, drain fat (if desired). Season with salt and pepper and add marinara. Mix to combine and set aside.
Next, prepare the peppers by slicing off the top (stem) and removing the ribs and seeds. Place them standing up in a square baking dish and place them in the oven. Bake for 10 minutes.
Meanwhile, prepare the ricotta filling. In a medium size mixing bowl, add the ricotta, Italian seasoning, garlic and onion powder and mix to combine.
Once the peppers have cooked, remove them from the oven and begin to add the filling starting with the beef. Add a tablespoon or two of the beef mixture to each pepper. Next, add a tablespoon or two of the ricotta mixture. Continue this pattern, alternating fillings until the peppers are full.
Top each pepper with mozzarella and cover with foil. Bake peppers for 20 minutes covered followed by 10 minutes uncovered, until the cheese is golden brown and ready to serve!