Preheat the oven to 350 degrees F (175 degrees C).

In a large pot, melt the butter over medium heat. Add the chopped green bell peppers, onion, and garlic. Cook and stir until the vegetables are slightly soft, about 2 minutes.

Add the ground Italian sausage and ground beef to the pot. Cook until the meat is crumbly and browned, stirring often, for about 10 to 12 minutes. Drain any excess grease from the pot.

Season the meat mixture with salt, black pepper, dried oregano, and garlic powder.

Mix in the diced tomatoes, cooked white rice, tomato paste, and Worcestershire sauce. Bring the mixture to a simmer and cook until heated through, about 5 minutes, stirring occasionally.

Pour the mixture into a large baking dish.

In a bowl, whisk together the condensed tomato soup and water until smooth. Pour the soup mixture over the meat mixture in the baking dish.

Spread the shredded Cheddar cheese evenly over the top of the casserole.

Bake in the preheated oven until the casserole is heated through and the Cheddar cheese is browned and bubbling, about 30 minutes.

Serve hot and enjoy your meaty stuffed pepper casserole!