Butter a quiche dish, or other similar shallow round dish. Preheat the oven to 325° F.
Sauté the spinach with a tablespoon of olive oil over medium-low heat for a minute or two stirring until wilted. Remove.
In a large bowl whisk together the eggs, heavy cream, and milk.
Add the spinach, onion, red pepper, ham and cheese. I usually reserve a small handful of the cheese and add it on top prior to putting it in the oven.
Add the egg mixture to the quiche dish. Sprinkle the top with any remaining cheese.
Bake at 325° F for 45-50 minutes or until the edges start to brown.
Notes
Cheese: We usually use either cheddar cheese, Monterrey jack, or a combination of both.
Spinach: You don't have to sauté the spinach before adding it to the dish. You can add it directly to the dish without sautéing it, but the frittata will take about 10 minutes longer in the oven because of the water content in the spinach. So to save cooking time, we often sauté it in a pan first.
Baking Dish: You can use a quiche dish, a pie dish, a square ceramic baker, or an oven-safe saute pan to make this frittata.
Salt: This recipe does not call for added salt because I find that the ham and cheese already have enough salt.