If you don't have cooked bacon, fry the bacon in bite-sized pieces in a non stick pan until cooked, but not too crispy. Place onto a paper towel lined plate and set aside.
Drain the bacon fat from the pan, and add some olive oil. Fry the diced potatoes over medium high heat, until golden brown and thoroughly cooked, turning often.
Beat the eggs, Parmigiano Reggiano cheese, parsley, about a tablespoon of water, salt and pepper.
When the potatoes are ready, sprinkle with a little salt, lower the burner to medium heat, then put the bacon back into the pan, dispersing evenly.
Now, add the beaten eggs.
With the corner of a spatula, cut into the frittata to allow the liquid egg to go through to the bottom of the pan, tipping the pan at times to also allow it to run to the edges. The goal is to try to cook the egg as much as possible before turning the frittata.
When the egg is mostly cooked, if you are a pro, you can flip the frittata in the pan! Or you can do what I do, which is place a large plate over the pan and turn it upside down, carefully, onto the plate, then slide it back into the frying pan.
If you don't mind it not looking perfect when finished, you can also cut it into "slices" like a pizza, and turn one piece at a time. Serve hot, on its own or with a salad, or other side dish. You decide how you like it best, because with frittata, the options are endless!