Preheat the oven to 375°F.

Slice the tops from the bell peppers, remove the stems, and set aside. Remove the internal seeds and membranes. Arrange the peppers open side up in a glass baking dish.

Finely chop the onion and pepper tops. Mince the garlic.

Set an extra-large skillet over medium-high heat and add the olive oil. Add the onion, peppers, garlic, ground beef, salt, black pepper, oregano, and thyme. Cook the beef and vegetables, breaking up the meat with a spatula, until it is thoroughly browned and the vegetables are soft, 7-8 minutes.

Add the diced tomatoes and cauliflower rice to the skillet, and stir to combine with the beef. Reduce the heat to medium-low and simmer for 2-3 minutes. Remove the skillet from the heat.

Divide the beef mixture evenly between each bell pepper, firmly packing it into the cavities. Sprinkle the top of each pepper with a tablespoon of shredded cheese.

Carefully pour enough water into the casserole dish to rise 1/2 inch up the sides of the peppers.

Spray a sheet of aluminum foil with nonstick cooking spray. Lay the foil sprayed side down over the peppers and secure around the edges of the casserole dish.

Bake the stuffed peppers on middle rack of oven until they can be easily pierced with a fork, about 50 minutes.

Remove the foil and continue baking until the cheese on top is golden brown, 10-15 minutes.

Check to see that stuffed peppers are done. Remove from oven or add time as needed.

Allow the peppers to rest for 5-10 minutes. Serve and enjoy.