Preheat oven to 400 degrees F.

Prep peppers: Cut 1/4-inch from tops of bell peppers and remove the stem, ribs and seeds. Fill a large baking dish with 1/2-inch of water.Place peppers cut-side down in the water and bake for 20 minutes.

Filling: Heat oil in a 12-inch skillet over medium-high heat. Add onion and cook until softened, about 5 minutes. Add garlic and cook for 30 seconds. Add corn, beans, diced tomatoes, green onions, chili powder, cumin, salt, and pepper. Stir until corn and beans are heated through, about 5 minutes. Remove skillet from heat and stir in rice, 1 cup cheese, and cilantro. Stir to combine. Taste and add additional seasonings, if needed.

Stuff peppers: Remove peppers from oven and drain water from dish. Divide the mixture evenly between the peppers, then top with remaining cheese.

Bake again: Return to oven for 10-15 more minutes, until peppers are tender and cheese is melted. Store leftover peppers in the refrigerator, covered for 4-5 days.