Preheat oven to 350°F.
Cut the ends off each end of the onion, peel, and then remove the inner layers. Your onion should be a bottomless, hollow shell, about ½" thick.
After all onions are peeled and hollowed-out, place them in a casserole dish.
In a medium-sized mixing bowl, combine the ground beef, egg, Italian seasoning, pork rinds, Parmesan cheese and Worcestershire sauce.
Press about one tablespoon of the meat mixture into each onion (the exact amount you use will depend on the size of your onions).
Press down with your fingers to compact the meat, making an indentation in the middle of your meet where you can insert a cube of cheese.
Fill your onions to the top with more meat mixture, to cover the cheese.
Bake for 35-45 minutes.
