Preheat oven to 375.

In a large skillet over medium heat, warm olive oil. Add onion and garlic and cook for 2 minutes.

Add the red pepper and spinach to the mix, a few handfuls at a time. Cook until spinach is wilted.

Meanwhile, combine milk, eggs, salt, pepper, and Italian seasoning in a medium bowl. Whisk together well.

Sprinkle 1/2 cup of the cheese on the bottom of the pie crust. Add the spinach mixture, pour the milk mixture over top, then sprinkle the rest of the cheese evenly on top.

Cover with foil and bake for 30 minutes.

Remove the foil, and continue to bake until quiche is lightly browned on top, around 15 minutes.

Let quiche cool, then cut into 8 slices.