Preheat oven to 350 degrees.

Beat egg whites using an electric mixer until stiff peaks form. Beat egg yolks until thick and lemon-colored; stir in half of the Canadian style bacon, cheese, half of the basil, and pepper. Fold yolk mixture into egg whites.

In a 9-inch skillet with oven-proof handle, heat 2 teaspoons of the butter over medium heat till a drop of water sizzles. Spoon egg mixture into skillet, gently smoothing surface. Cook for 3 to 4 minutes or until the bottom is golden.

Bake in oven for 5-6 minutes or until knife inserted halfway between center and outer edge comes out clean.

Meanwhile, in skillet cook the remaining Canadian style bacon, mushrooms and green pepper in the remaining hot butter over medium heat 3 minutes or until tender. Add the remaining basil and tomato; cook 5 minutes or till liquid is reduced, stirring occasionally.

Loosen sides of omelet with a spatula. Make a shallow cut across omelet, cutting slightly off-center. Spoon filling over larger half. Tip skillet or using spatula, fold the smaller portion of omelet over larger half. Slip omelet onto a warm serving platter. Serve immediately.