In a frying pan over medium heat sauté the onions and garlic with the olive oil.
Drain the can of marinated artichokes and then pat dry with paper towels. Add to the frying pan and continue to sauté until soft. Set aside.
Preheat the oven to 350°F
Grease the casserole dish with butter and then evenly sprinkle a ¼ cup of grated parmesan over the butter. Transfer the artichoke mixture to the casserole and spread out evenly.
In a large bowl whisk together the eggs, cream, shredded cheddar, oregano and nutmeg until frothy.
Gently pour egg mixture over the artichoke mixture in the casserole dish, spread out evenly if needed.
Bake at 350°F for 30 minutes, remove from oven and sprinkle the top with the remaining parmesan and place back in the oven for another 6 minutes. The frittata should be slightly golden on top when done.
Top Tip: strain the marinated artichokes and pat dry, otherwise there will be too much moisture and make the frittata watery.