- 2 1/4 pounds summer squash, quartered lengthwise and thinly sliced crosswise
 - 2/3 cup finely chopped yellow onion
 - 1 (4 ounce) can chopped green chiles
 - 1 (4.5 ounce) can chopped jalapenos, drained
 - 1/2 teaspoon salt, or to taste
 - 2 1/4 cups grated extra-sharp Cheddar cheese, divided
 - 1/4 cup all-purpose flour
 - 3/4 cup mild salsa
 - 4 scallions, thinly sliced, for garnish
 - 1/4 cup finely chopped red onion for garnish
 
- Preheat oven to 400 degrees 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.