In a non-stick skillet with over medium-low heat, melt 1 tsp. of the butter. Add the sliced mushrooms. Cook a minute or so until they just start to brown and caramelize.

Add the green and yellow sliced zucchini, and the baby spinach.

Cook a few minutes until the zucchini starts to brown and the spinach is wilted. Once cooked, remove from pan and set aside.

Melt the other Tsp. of butter in the same pan. While the butter is melting, crack the 3 eggs into a bowl. Using a fork, whip the eggs until well blended. Then pour into the pan once all the butter is melted. Swirl the eggs in the pan to cover the whole bottom of the pan. Add any salt and pepper you wish to add. Cover the pan and cook for a minute or two. Until the eggs are 3/4 of the way set. (I just use the plate I will be serving the omelet on - keeps the plate warm for serving).

Once the eggs are almost set, remove the cover and distribute the sliced cheese on top. Turn off the heat and using a spatula to help remove the eggs, slide them out of the pan and onto the plate. Then add the already cooked vegetables on top of half of the eggs.

Now all that is left to do is fold the side of the eggs without any vegetables on it over the vegetables. Top with the diced tomatoes.