Heat olive oil in a wide pan over medium-high heat.
Once the oil is hot, add garlic and fry for 20-30 seconds.
Add onions and fry until they turn pink in color, stirring frequently.
Now add mushrooms and cook for 5-6 minutes. Stir frequently while cooking.
Add parsley, salt, and black pepper to the pan and mix well.
Cook until the mushrooms are dried stirring frequently. Remove the pan from the heat and set it aside.
Heat a 6-inch non-stick pan over medium-low heat. Lightly brush the pan with oil.
Pour the whisked eggs into the pan.
Cover the pan with a lid and cook undisturbed until the eggs are 90% cooked.
Remove the lid and keep 2-3 tablespoon of mushroom filling on one-half of the eggs. Keep some chopped spinach and grated cheese on top.
Fold the omelette in half. Transfer to a serving plate and serve hot.