Heat 2 tablespoons of olive oil in a large skillet over medium heat.
Add spinach and cover. Allow to cook for 10 minutes stirring occasionally.
In another skillet over medium heat, add the remaining tablespoons of olive oil.
Heat and add 1/4 cup of mushrooms, stirring occasionally. The mushrooms should turn a dark reddish brown when ready; about 10 minutes.
In a bowl, crack egg and whisk.
Heat a small nonstick pan or skillet over medium-high heat until hot.
Pour in egg which should set immediately at edges.
Push portions from edges toward the center with a spatula so that uncooked eggs can reach the pan’s surface.
Continue cooking and moving cooked portions as needed.
When top surface has no visible liquid egg, fold omelet in half with spatula.
Turn off heat and set aside.
Toast 1 slice of bread and put on plate.
Top with sauteed spinach, mushrooms, omelet, and sliced tomatoes.
Garnish with a pinch of salt and pepper and enjoy!