egg bake recipe

- 8 large eggs - 1/2 cup milk (whole, 2%, or your preferred type) - 1/2 teaspoon salt - 1/4 teaspoon black pepper - 1 cup shredded cheddar cheese (or your favorite cheese) - 1 cup spinach leaves, chopped - 1/2 cup bell pepper, diced (any color) - 1/2 cup cherry tomatoes, halved - 1/4 cup red onion, finely chopped - 1/2 cup mushrooms, sliced (optional) - 1 tablespoon olive oil - Fresh parsley, chopped (for garnish, optional)