Spinach Mushroom Frittata

1 tablespoon + 1 teaspoon extra virgin olive oil, divided
2 cups sliced mushrooms such as shiitake, morels, etc. or button mushrooms
2 cups chopped fresh spinach
6 eggs 
4 tablespoons chopped fresh chives
2 tablespoons chopped fresh parsley
1/4 teaspoon salt
1/4 teaspoon freshly ground black pepper
1/2 cup shredded pecorino Romano cheese,  divided

1. Arrange oven rack 6 inches from the broiler. Heat broiler to high. 
2. Heat 1 tablespoon olive oil in a medium-size cast iron skillet over high heat.  Add the mushrooms and cook 2 minutes, stirring frequently. Reduce the heat to medium-high and add the spinach and toss with mushrooms to coat with oil. Cook in skillet for 1 minute more.
3. While the mushrooms are cooking, whisk together the eggs, herbs, salt, pepper, and 1/4 cup of the cheese in a bowl. Add the remaining teaspoon oil to the pan, stirring the vegetables to coat. Pour the egg mixture over the mushrooms and spinach and reduce heat to medium-low. Cook for 1 1/2 minutes, running a rubber spatula around the edges of the pan to keep the eggs from sticking.
4. Sprinkle the remaining 1/4 cup cheese over the egg mixture and place under the broiler for 2 ½ –3 minutes or until frittata is golden brown and lightly puffed. Remove the frittata from the oven and let cool a minute or two. Cut and serve immediately.