Bring 4 quarts water to boil in large stockpot or Dutch oven over high heat. Add 1 tablespoon salt and bell peppers. Cook until peppers just begin to soften, about 3 minutes. Using slotted spoon, remove peppers from pot, drain off excess water, and place peppers cut-sides up on paper towels. (I like a firm bite to my veggies so I would skip this step and just stuff the raw peppers, but it’s up to you - either way is fine.)
Return water to boil; add rice and boil until tender, about 13 minutes. Drain rice and transfer to large bowl; set aside. (If you skip boiling the peppers, just make some rice, a couple servings, using your usual method.)
Adjust oven rack to middle position and heat oven to 350 degrees.
Meanwhile, heat 12-inch heavy-bottomed skillet over medium-high heat until hot, about 1 ½ minutes; add oil and swirl to coat. Add onion and cook, stirring occasionally, until softened and beginning to brown, about 5 minutes.
Add ground beef and cook, breaking beef into small pieces with spoon, until no longer pink, about 4 minutes. Stir in garlic and cook until fragrant, about 30 seconds.
Transfer mixture to bowl with rice; stir in tomatoes, 1 cup cheese, parsley, and salt and pepper to taste.
Stir together ketchup and reserved tomato juice in small bowl.
Place peppers cut-side up in 9-inch square baking dish (use pepper tops standing on edge in between each pepper to help prop them up). Divide the filling evenly among the peppers. Spoon 2 tablespoons ketchup mixture over each filled pepper and sprinkle each with 1 tablespoon of remaining cheese.
Bake until cheese is browned and filling is heated through, 25 to 30 minutes. Serve immediately.
This recipe is pretty simple and classic and a great starting point. To elevate the dish you might consider the following: Use ground chuck for a fattier, tastier option. Use leaner beef or substitute ground chicken or ground turkey for a healthier option. Use hot Italian sausage or chorizo for a spicy or bolder flavor. Use red pepper flakes, basil, oregano, or finely diced adobo peppers to give it a different flavor. Or add a dash of Worcestershire or A-1 sauce to deepen the flavor and counter the sweetness of the ketchup, or replace the ketchup entirely with marinara sauce and the Monterey Jack with Mozzarella and Parmesan for an Italian version. Have fun with it!
