Creating the Spinach and Feta Breakfast Casserole can be simple if you follow these steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish.
2. Sauté Vegetables: In a skillet, heat olive oil over medium heat. Add chopped onions and bell peppers, sautéing until softened, about 5 minutes. Add chopped spinach and cook until wilted, about 2-3 minutes. Remove from heat.
3. Whisk Eggs and Milk: In a large bowl, whisk together eggs and milk until well combined.
4. Season the Mixture: Stir in garlic powder, salt, black pepper, and oregano to the egg mixture.
5. Combine Ingredients: Add the sautéed vegetables and crumbled feta cheese to the egg mixture, stirring to combine evenly.
6. Pour into Baking Dish: Pour the mixture into the prepared baking dish. If using, sprinkle shredded cheese on top.
7. Bake: Place the casserole in the preheated oven and bake for 30-35 minutes, or until the eggs are set and the top is golden.
8. Cool Slightly: Once baked, remove it from the oven and let it cool for about 5 minutes before slicing.
9. Slice and Serve: Cut into squares and serve warm.

By following these steps, you’ll create a delicious Spinach and Feta Breakfast Casserole that everyone will love!