Cut the bell peppers in half from top to bottom, remove the stem, seeds and any inside bits. Set aside.
In a large skillet, add the ground beef and cook on a medium to high heat until everything is cooked and browned. Add the onions and garlic and cook for 3-4 minutes on medium to low heat. Drain any excess grease.
Add the ketchup, mustard, chili powder, paprika, brown sugar, and Worcestershire sauce to the beef; stir until everything is combined. Add ¼ cup of water and stir once again. Bring to a simmer and cook for 10 minutes or until everything has thickened up.
Evenly add the sloppy Joe mixture into the peppers using a spoon.
To a large baking dish, add peppers. Divide the mixture evenly into the pepper halves and top with cheese. Cover with foil and bake until peppers are tender, about 45 minutes. Uncover and broil until cheese is golden, 1-2 minutes.
Notes
If the sloppy joe mixture is too thin, simmer it for a few extra minutes until it thickens up to your desired consistency. This ensures the filling stays inside the peppers during baking.
Adjust the seasoning and sweetness of the sloppy joe sauce to your taste preferences. You can add more or less chili powder, brown sugar, or Worcestershire sauce to suit your liking.
Cover the baking dish with foil during the initial baking time to help the peppers cook through evenly. Remove the foil during the last few minutes of baking to allow the cheese to melt and become golden brown under the broiler.