1canfire-roasted diced tomatoes with juices(15 ounces)
1cupcooked brown riceor farro, quinoa, cauliflower rice, or orzo (if using orzo, undercook it slightly)
1/2cupshredded sharp cheddar cheese
1/2cupshredded pepper jack cheeseor additional cheddar
For serving: chopped fresh parsley or cilantro
Preheat your oven to 375°F. Lightly coat a 9×13-inch baking dish with nonstick spray. Slice the bell peppers in half from top to bottom down through the stem. Remove the seeds and membranes, then arrange cut side up in the prepared baking dish.
Heat a Dutch oven or similar deep, wide skillet over medium-high. Add the beef and onion. With a wooden spoon or spatula, break the meat into small pieces. Cook and stir until the meat is browned and fully cooked and the onion is tender, about 7 minutes. Drain off any excess fat.
Stir in the Italian seasoning, cumin, garlic powder, salt, and pepper. Let cook for 30 seconds.
Stir in the spinach a few handfuls at a time, cooking until it wilts down; this will take between 1 and 2 minutes.
Pour in the can of diced tomatoes along with the juices. Let simmer for 1 minute.
Remove the pan from the heat. Stir in the rice (or your grain of choice), 1/4 cup of the cheddar, and 1/4 cup of the pepper jack. Taste and add additional salt and/or pepper as desired.
With a spoon, mound the filling inside the peppers, then top with the remaining cheeses. The peppers will be very full.
Pour a bit of water into the pan with the peppers—just enough to scantly cover the bottom of the pan. I like to put the water in a liquid measuring cup, then carefully pour it around the outside (be careful not to pour it into the peppers themselves).
Bake the stuffed peppers uncovered for 30 to 35 minutes, or until the peppers are tender and the cheese is melted. Top with parsley or cilantro. Serve hot.
TO STORE: Refrigerate stuffed peppers in an airtight storage container for up to 4 days.
TO REHEAT: Rewarm leftovers in a baking dish in the oven at 350 degrees F.
TO FREEZE: Freeze peppers in an airtight freezer-safe storage container for up to 3 months. Let thaw overnight in the refrigerator before reheating.
TO MAKE AHEAD: Cut and core the bell peppers up to 1 day in advance, and refrigerate them in an airtight storage container. Cook the filling as directed up to 1 day in advance. Let cool, then refrigerate it in a separate airtight storage container. Fill and bake peppers as directed just before serving.