Instructions

• Preheat the oven to 350°.
• Pierce the squash with a fork in several places. Microwave on high for 12 minutes, rotating at least once. Let the squash cool, then cut in half, lengthwise, and scoop out the seeds with a spoon. Scoop out the flesh into a large bowl. Add zucchini, onions and tomato sauce. Season with salt and pepper. Spoon the mixture into a three-quart shallow baking pan. Bake for 40 to 45 minutes.
• Next, make the caramelized onions by heating canola oil in a large nonstick skillet over low heat. Add the onions and cook for 30 minutes, stirring often, until soft and brown.
• Remove the baking pan from the oven and turn the oven to broil. Top the casserole with the grated cheese and place under the broiler until golden brown, about 5 minutes. Let sit for 5 to 10 minutes before serving. Let cool and store in a covered container in the refrigerator for up to three days.