Preheat your oven to 350°F (175°C).

Grease a 9x13-inch baking dish with butter or non-stick spray.

In a skillet, heat about 2 tablespoons of olive oil over medium heat. Add the finely chopped onions, green bell peppers, and sliced mushrooms to the skillet and sauté for about 5 minutes until tender.

In a large bowl, crack in 12 eggs and pour in 1 cup of milk. Whisk with salt, black pepper, and garlic powder until smooth.

Fold in the sautéed vegetables, diced ham or bacon, and 1.5 cups of shredded cheddar cheese. Stir gently.

Pour the mixture into the prepared baking dish, spreading it evenly.

Sprinkle the remaining 0.5 cup of shredded cheese over the top of the mixture.

Bake for 30-35 minutes until the eggs are set and golden brown on top.

Remove from the oven and let cool for 5 minutes before serving.