Chiles and cheese turn mild summer squash into a zesty, satisfying casserole. The jalapenos make this dish quite hot; if you prefer a milder version, use a second can of diced green chiles instead.
- Preheat oven to 400°F. Coat a 9-by-13-inch baking dish with cooking spray.
- Combine squash, onion, chiles, jalapenos, salt and 3/4 cup cheese in a large bowl. Sprinkle with flour; toss to coat. Spread the mixture in the prepared baking dish and cover with foil.
- Bake the casserole until it is bubbling and the squash is tender, 35 to 45 minutes. Spoon salsa over the casserole and sprinkle with the remaining 1 1/2 cups cheese. Bake, uncovered, until golden and heated through, 20 to 30 minutes. Sprinkle with scallions and red onion.