Whisk 2 eggs with salt and black pepper until well combined.
Heat olive oil in a nonstick skillet over medium heat. Arrange the sliced tomatoes in the pan.
Pour the beaten eggs over the tomatoes and gently tilt the pan to spread evenly. Sprinkle with chopped green onion and a little mozzarella cheese.
Cover and cook for 2–3 minutes until the eggs begin to set.
Place a tortilla over the eggs and gently press it down. Carefully flip everything over using a plate.
Melt the unsalted butter in the skillet. Return the tortilla to the pan, tortilla side down.
Sprinkle some mozzarella cheese over one half of the tortilla. Add the cooked bacon crumbles or ham, then sprinkle more mozzarella on top.
Fold the tortilla in half. Cook until the bottom is golden brown, then carefully flip it over.
If desired, sprinkle a little extra mozzarella cheese on top. Cover and cook for another 2–3 minutes until golden brown and the cheese has melted.
Transfer to a serving plate, garnish with parsley, slice, and enjoy!