1. Preheat oven to 375°F (190°C) and grease a 9×13 inch casserole dish.

2. In a skillet, heat olive oil over medium heat, cook onion until translucent, add garlic and cook one minute.

3. Add sliced squash to the skillet and cook 5 minutes until tender, then stir in spinach until wilted and remove from heat.

4. In a large bowl, whisk eggs and milk, season with salt, pepper, and herbs, and stir in half of the shredded cheese if using.

5. Spread the sautéed vegetables evenly in the prepared dish, sprinkle corn kernels on top, and pour the egg mixture over the vegetables.

6. Top with remaining cheese and breadcrumbs if desired.

7. Bake uncovered for 30 to 35 minutes until set and lightly browned on top.

8. Let rest 5 minutes before serving.