Over medium-high heat, add the steak to a large pan and break it apart while it cooks.
Once the steak is browned, drain any extra grease.
Cook for five to seven minutes after adding the olive oil, onions, and garlic and reducing the heat to medium.
Return the ground beef to the pan and stir in the rice, water, Worcestershire sauce, tomato sauce, kosher salt, black pepper, and Italian seasoning.
Pack the mixture down gently after scooping it into the bell peppers.
Add ½ of the Parmesan cheese on top.
Fill your slow cooker with beef stock, then gently add the bell peppers to the saucepan.
Simmer for 7–8 hours on low.
Before serving, sprinkle the remaining Parmesan cheese over top.