Make sure that you use a cast iron or a oven safe skillet.
3 tablespoons extra-virgin olive oil
12 ounces Italian sausage, crumbled (uncured)
½ large yellow onion, finely chopped
2 cups fresh spinach, coarsely chopped
1 cup ricotta cheese
1 cup Portabella mushrooms, coarsely chopped
½ teaspoon sea salt
¼ cup freshly-grated Parmesan cheese
Preheat oven to 350º F.
In a medium-sized bowl, whisk eggs, then stir in 2 tablespoons olive oil.Set aside.
In an oven-safe skillet over medium heat, sauté sausage and onions in one tablespoon olive oil until onions sof-tened and slightly browned and sausage fully cooked.Add salt and pepper.
Add the spinach, stir and cover until wilted, generally about 2 minutes.Add the ricotta cheese, mushrooms, and salt.Pour in egg mixture and mix together well.Cover over low to medium heat for 3 minutes.
Remove cover, sprinkle Parmesan cheese over top and place pan in oven for 20 minutes.
Remove (using oven mitt!)from oven.Cool for five minutes then, using a spatula, release the frittata around the edges and under the bottom.Slice and serve.