Beat eggs, cheese, Italian seasoning and pepper with a fork; reserve. Cut strip of pepperoni lengthwise into thirds; separate pieces. Heat butter in 12 inch nonstick skillet until melted. Cook and stir pepperoni, red and green bell pepper and onion in margarine over Medium heat until onions are translucent, about 3 minutes. Spread mixture evenly in bottom of skillet.
Pour reserved egg mixture evenly over pepperoni mixture in pan. Reduce heat to Medium-Low. Cook, uncovered, lifting edges of omelet to let uncooked egg run underneath, until eggs are almost set and golden brown on bottom, about 6 minutes. Place at least 12 inch plate over skillet; invert omelet on plate. Slide omelet back into skillet. Cook until eggs are set and golden brown on bottom, about 3 minutes.
Per serving: 195 calories, 12 g protein, 3 g carbohydrate, 15 g fat, 290 mg cholesterol, 360 mg sodium 160 mg potassium