Crack the eggs into a bowl, add a pinch of salt and pepper, and whisk vigorously until fully combined and slightly frothy.
Place your non-stick skillet over medium heat and add a teaspoon of butter or oil, allowing it to melt and shimmer, coating the pan evenly.
Add the sliced mushrooms to the skillet and sauté for about 3 minutes until they turn golden and release a nutty aroma.
Stir in the fresh spinach and cook for another 1-2 minutes until it wilts and brightens in color, filling the air with a fresh aroma.
Pour the beaten eggs evenly over the sautéed vegetables, tilting the pan to spread them out into an even layer.
Reduce the heat to low and let the eggs cook gently for 2-3 minutes until the edges are lightly golden and the surface is mostly set but still slightly moist.
Sprinkle cheese and herbs over the top if using, then fold the omelette in half or slide it onto a plate, allowing it to rest for 30 seconds to finish setting.
Gently slide or fold the omelette onto a plate, revealing a tender, moist interior with lightly crisped edges and vibrant fillings.
Slice into halves or serve whole, garnished with extra herbs if desired, and enjoy this simple, satisfying breakfast.