Preheat broiler and place heating rack 4-5" from the heating element. Microwave fresh spinach in a loosely covered bowl on high for about 3 minutes or until it is slightly wilted. Dry spinach thouroughly with paper towels and chop it coarsely.
Meanwhile, coat bottom and sides of a 12" ovenproof skillet with cooking spray. Heat 1 Tbs. oil in the skillet on med-high and add onion. Cook until lightly browned.
In a large bowl, beat eggs thoroughly. Stir in tomatoes, spinach, cheese, Italian seasoning, salt & pepper.
Add remaining 2 teaspoons oil to the skillet with onion and tilt pan to distribute oil evenly. Pour egg mixture in, evenly distributing vegetables with the back of a wooden spoon. Cook over medium heat without stirring for about 7 minutes or until only te surface is loose.
Place skillet under broiler and cook for approximately 2 minutes or until surface is lightly browned. To serve, loosen edges with a knife, flip it onto a cutting board and slice.