In a medium size frying pan (the best non stick you have) add 2 tablespoons olive oil, the chopped asparagus, onion, pancetta (if using), salt, parsley and water, mix, cover and cook on low to medium heat until asparagus is tender and water has evaporated, (using a fork coarsely mash the asparagus mixture).
In a small bowl add the eggs and beat well with a fork (this should be done just before adding to the asparagus mixture). Add egg mixture to the hot asparagus mixture, and with a wooden spoon mix to combine. Let cook for approximately 10 minutes (moving the frying pan back and forth to make sure the egg doesn't stick, or cheat like I did and with a plastic spatula carefully lift frittata on all sides and underneath to unstick). Using a large dish place it over the frying pan and flip the frittata onto the plate
Drizzle a little olive oil onto the frying pan and slide the frittata back into the frying pan, cook for approximately another 10 minutes. Serve immediately. Enjoy!