1. Beat the eggs in a bowl, add milk, salt and pepper.
2. Into a frying pan, melt 1/2 tbsp butter with 1 tbsp olive oil. Fry onion for 5 min or till golden. Add chopped mushrooms, bell pepper and tomato. Cook for 10 min. Set aside.
3. On a low heat, melt 1/2 tbsp butter in a frying pan. Add 1 tbsp olive oil and turn heat up to medium. After a minute (when the oil is heated) add the eggs and swirl the pan to have an even surface. Cook on low-medium heat till the pancake's bottom turns golden.
4. Pour the cooked mixture of vegetables onto the half of pancake surface. Add feta cheese, mozzarella (optional) and parsley, then fold the pancake over the mixture. Cook for 1-2 min and serve.