1. Preheat oven to 350°F (175°C) and grease a 9×13-inch baking dish.

2. In a skillet over medium heat, melt butter and sauté squash and onion until tender, about 8–10 minutes; drain off any excess liquid.

3. In a bowl, whisk together eggs, milk, shredded cheese, salt, pepper, garlic powder, and paprika.

4. Fold the drained squash and onions into the egg and cheese mixture until evenly coated.

5. Pour the mixture into the prepared baking dish and spread evenly.

6. In a small bowl, combine breadcrumbs with a bit of melted butter and sprinkle evenly over the casserole.

7. Bake uncovered for 25–30 minutes until the topping is golden and the casserole is set.

8. For an extra-crispy top, broil for 1–2 minutes, watching carefully to prevent burning.

9. Let rest for 5 minutes before serving.