01 - Preheat oven to 350°F. Grease a 9-inch pie dish with olive oil.
02 - Arrange the cherry tomatoes, spinach, and red onion evenly across the bottom of the prepared pie dish.
03 - Sprinkle the mozzarella and Parmesan cheeses evenly over the vegetables.
04 - In a large bowl, whisk together the eggs, milk, olive oil, Italian herbs, garlic powder, salt, and pepper until well combined.
05 - Gradually whisk in the flour until the batter is smooth and free of lumps.
06 - Pour the batter over the vegetables and cheese in the pie dish. Bake for 40 minutes, or until the pie is set, puffed, and golden brown on top.
07 - Remove from the oven and let cool for 5 to 10 minutes before slicing and serving.