Wash and chop the bell peppers, zucchini, and onions into even pieces.

In a large mixing bowl, combine cream of mushroom soup, garlic powder, and onion powder.

Layer the rice or quinoa as the base in the Instant Pot, followed by the chopped vegetables, and then pour the sauce over everything.

Seal the lid of the Instant Pot and cook on high pressure for 10 minutes.

Perform a quick release of the pressure and check for doneness.

Sprinkle the cheddar and mozzarella cheese on top, replace the lid, and let it melt for 3-5 minutes.

Serve the casserole warm in bowls, optionally pairing it with a side salad or cornbread.