Start by washing your fresh baby spinach leaves thoroughly. Drain them and set them aside. If your mushrooms are large, slice them into thin pieces to ensure even cooking.
In a mixing bowl, crack the three eggs and whisk them vigorously until the yolks and whites are fully combined. Season with a pinch of salt and freshly ground black pepper to taste.
Heat a non-stick skillet over medium heat and add a splash of cooking oil or a small pat of butter. Once the oil is hot, add the sliced mushrooms. Sauté for about 3-4 minutes until they are tender and slightly browned.
Toss in the fresh spinach leaves with the mushrooms and cook for an additional 1-2 minutes, just until the spinach wilts. Stir occasionally to combine the flavors.
Spread the mushroom and spinach mixture evenly in the skillet and reduce the heat to low. Pour the whisked eggs over the vegetables, ensuring even coverage. Allow the omelet to cook undisturbed for about 3-5 minutes, or until the edges start to lift and the bottom is set.
Sprinkle the shredded cheese over one half of the omelet. Using a spatula, carefully fold the other half over the cheese. Let it cook for another minute until the cheese melts and the omelet is fully cooked.
Gently slide the omelet onto a plate and cut it in half for easy serving. Enjoy your Mushroom and Spinach Omelet hot, perhaps with a side of toast or fresh fruit for a complete meal.
