In a large bowl, combine the eggs, milk, mayonnaise and seasonings. Whisk until thoroughly combined.
Stir in the spinach and cheese.
Add the mixture to the pie crust and cover it with aluminum foil.
Bake for about 55 minutes then remove the foil and bake for an additional 10 minutes or until eggs are cooked thoroughly.
Notes
If you use light mayonnaise, it won't stay mixed when you add it to the eggs. So once you mixed all the ingredients, place it in the oven to bake immediately.