Place pepper halves, open side up, into a medium skillet or casserole dish.
Brown ground beef with the Worcestershire sauce in a large skillet over medium heat. Remove from heat and drain any drippings from the skillet. Stir in onion, garlic, oregano and salt. Spoon ground beef mixture into the openings of the peppers.
Mix together cornbread mix, egg, buttermilk, Parmesan, and parsley. Spoon over top of filled peppers and bake until cornbread topping has cooked through and lightly browned, about 14 - 15 minutes. Remove from oven and serve.