Squash, Egg, and Cheese Casserole

2 tablespoons vegetable oil

3 summer squash, sliced

1 small onion, diced

4 eggs, beaten

2 tablespoons milk

3 cups shredded Cheddar cheese, divided

2 tablespoons white sugar

2 tablespoons all-purpose flour

¼ teaspoon salt

¼ teaspoon ground black pepper

6 tablespoons butter, melted

Preheat oven to 375 degrees F (190 degrees C).

Heat vegetable oil in a large skillet over medium heat, and cook the summer squash and onion until tender, about 10 minutes. Stir occasionally.

While the squash are cooking, mix together the eggs, milk, 1 cup of Cheddar cheese, sugar, flour, salt, and black pepper in a large bowl. Stir in the squash mixture and melted butter; turn into a 2-quart casserole dish. Top with the remaining 2 cups of Cheddar cheese.

Bake in the preheated oven until the casserole is set and the cheese topping is crisp and starting to brown, 35 to 45 minutes. Allow to stand for 15 minutes before serving.