Chop one cup each of fresh mushrooms and baby spinach.
Sauté mushrooms in skillet for 3 minutes and then add in the spinach and continue to sauté for an additional 2 minutes.
Remove spinach and mushrooms from skillet and drain on paper towels.
In mixing bowl add 5 whole eggs and 3 egg whites, one table spoon of water and season with salt and pepper to taste. Then mix in spinach and mushrooms and swiss cheese.
Turn oven on to 400 °F (200 °C). Wipe out skillet and spay with cooking spray like Pam - pour in egg mixture and cook on medium. When sides start looking brown put on lid. Cook for 5 minutes on stove top.
When eggs are slightly firm put skillet in oven without lid. Cook another 3 minutes or until firm and top is slight brown.
Cool slightly and then slide out of pan and cut into 6 slices.
There are 145 calories in 1 serving of Mushroom and Spinach Frittata.