Prepare the Vegetables and Meat (If Using):

1. Preheat the Oven: Preheat your oven to 375°F (190°C). Grease a 9-inch pie dish or quiche pan with olive oil or butter, or line it with parchment paper.

2. Cook the Vegetables: Heat the olive oil in a large skillet over medium heat. Add the diced onions and cook for 2-3 minutes, or until soft and translucent. Add the diced bell peppers, sliced mushrooms, and spinach (if using). Cook for another 5-7 minutes, stirring occasionally, until the vegetables are tender. Remove from heat and set aside to cool slightly.

3. Cook the Meat: If using halal chicken sausage or turkey, crumble and cook the meat in the same skillet over medium heat for 5-7 minutes until browned and cooked through. Set aside to cool slightly.

Mix the Egg Base:

4. Whisk the Eggs: In a large bowl, crack the eggs and whisk them well. Add the milk, garlic powder, oregano, salt, and pepper. Whisk until everything is combined and the mixture is smooth.

Assemble the Quiche:

5. Combine Vegetables and Cheese: Add the cooked vegetables, meat (if using), and 1 cup of shredded cheese to the egg mixture. Stir gently to combine, making sure the ingredients are evenly distributed.

6. Pour the Mixture Into the Pan: Pour the egg and vegetable mixture into the prepared pie dish or quiche pan. Smooth the top with a spatula to ensure an even layer.

7. Add Additional Cheese: Sprinkle the remaining ½ cup of shredded cheese on top of the quiche for a golden, cheesy finish.

Bake the Quiche:

8. Bake: Place the quiche in the preheated oven and bake for 30-35 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean.

9. Cool: Once the quiche is done, remove it from the oven and allow it to cool for 10-15 minutes before slicing. This will help the quiche set and make it easier to cut into neat slices.

Cut and Serve:

10. Serve: Slice the quiche into wedges or squares and serve warm. Pair it with a light salad or fresh fruit for a well-rounded meal.