In a large skillet, heat the butter over medium heat. Once it's melted, add the onion and mushrooms. Cook for 3 or so minutes, then add the zucchini and corn. Cook until everything has a chance to soften, about 5 or so minutes, then stir in the garlic and cook for another minute or so before removing the pan from the heat. Make sure to strain out any excess liquid in the pan, then place the veggies in a large bowl and let them cool for just a few minutes.

Preheat the oven to 375°F. Line a 9" pie dish with parchment paper. Once the veggies have cooled slightly, stir in the seasonings, beaten eggs and most of the cheese (reserve a handful for topping). Pour the veggie mix put into the lined pie dish and sprinkle the extra cheese evenly over the top.

Bake for 25 or so minutes, until the center is completely set and cooked through. Check on it at about halfway through and if its browning too quickly, then loosely cover it with foil. Once it's done, remove it from the oven and let it sit for 10 or so minutes before slicing and serving.