preheat the oven to 180° celsius
first defrost the spinach, I do that in my microwave oven, and press out excess fluid.
then fill the spinach in an oven form and spread evenly.
add the fries (I cut them in smaller pieces) and the chorizo.
Now mix the egg with the milk and add salt and pepper to taste.
Pour the egg-milk mixture over the spinach, fries and the chorizo and
sprinkle with cheese (feel free to add more cheese, but recalculate nutrition)
put the form into your oven (middle) and cook for around 20 minutes. The ovenfrittata is done when it doesn´t move anymore when you shake the form a bit.