Preheat the oven to 375 degrees. Coat a round pie dish with olive oil cooking spray.
Layer potato slices all over the edges and bottom of the pan, overlapping them. Season the potatoes with sea salt and freshly cracked black pepper to taste. Coat the potatoes with olive cooking spray.
Bake for 20 minutes. Remove from the oven and set aside.
Meanwhile, heat the butter or olive oil in a large skillet over medium heat. Add the onions and season with sea salt, and cook, stirring often, for 10 minutes, or until golden brown and tender.
Sprinkle the potato crust with caramelized onion, green chile, diced tomato, and cotija cheese.
Whisk the eggs with the milk and season with sea salt and freshly cracked pepper to taste.
Pour the egg mixture over the veggies and ham.
Place in the oven and bake for 30-40 minutes, or until a tester inserted in the center comes out clean–don't overcook.
Remove from the oven and let cool for a few minutes before slicing. Enjoy.