Creating your Crustless Tuna Breakfast Quiche can be a breeze if you follow these simple steps:

1. Preheat Oven: Begin by preheating your oven to 350°F (175°C).
2. Prepare Baking Dish: Lightly grease a 9-inch pie dish or quiche dish with cooking spray or olive oil.
3. Cook Vegetables: In a skillet, sauté the diced onions and bell peppers over medium heat until they are soft, about 5 minutes. If using fresh spinach, add it in the last minute to wilt it slightly.
4. Mix Eggs and Milk: In a large bowl, crack the eggs and whisk them together with the milk until well combined.
5. Add Seasonings: Stir in garlic powder, Italian seasoning, salt, and pepper to the egg mixture.
6. Combine Ingredients: Add the sautéed vegetables, drained tuna, and shredded cheese into the egg mixture. Gently fold everything together until combined.
7. Pour Mixture: Pour the mixture into the prepared baking dish, spreading it evenly.
8. Bake: Place the dish into the preheated oven and bake for 25-30 minutes, or until the quiche is set and the top is golden brown.
9. Cool Slightly: Once baked, remove it from the oven and let it cool for a few minutes before slicing.
10. Slice and Serve: Cut into wedges and serve warm, or refrigerate for later use.

Following these steps will lead you to a delightful Crustless Tuna Breakfast Quiche that promises to satisfy your taste buds!