In a large saucepan, bring 1/2 in. of water to a boil. Add spinach; cover and boil for 3-5 minutes or until wilted. Meanwhile, in a large bowl, whisk the eggs, pimientos, Italian seasoning and parsley; set aside.
Drain spinach and pat dry. In a 7-in. ovenproof skillet, saute mushrooms and onions in butter and oil until tender. Reduce heat; sprinkle with spinach, cheese and salt. Top with egg mixture. Cover and cook for 4-6 minutes or until nearly set.
Uncover skillet. Broil 3-4 in. from the heat for 2-3 minutes or until eggs are completely set. Let stand for 5 minutes before cutting.