Preheat your oven to 350°F (175°C).
In a large bowl, combine the squash, zucchini, onion, red and green bell peppers, and 1 cup of the cheese.
In a separate small bowl, mix together the bread crumbs, olive oil, salt, and pepper.
Transfer the vegetable mixture to a baking dish and top with the bread crumb mixture.
Bake for 30 minutes, or until the vegetables are tender and the top is golden brown.
Remove from the oven and sprinkle the remaining 1 cup of cheese on top.
Return the casserole to the oven and bake for an additional 5 minutes, or until the cheese is melted and bubbly.
Serve hot and enjoy!
