Crumble sausage into a 10-in. ovenproof skillet; cook over medium heat until no longer pink. Drain and set aside. In the same skillet, saute the onions, mushrooms, garlic and seasonings in oil until vegetables are tender. Add spinach in batches; cook over medium-low heat for 3-4 minutes or until spinach begins to wilt.
In a large bowl, whisk eggs and hot pepper sauce. Return sausage to skillet; add egg mixture. As eggs set, lift edges, letting uncooked portion flow underneath. Cook until eggs are nearly set, about 8-10 minutes.
Meanwhile, preheat broiler. Broil egg mixture 6 in. from the heat for 30-60 seconds or until set. Sprinkle with cheese; broil 30 seconds longer or until melted. Cut into wedges. Serve immediately.