Adjust the oven rack to the upper-middle position and preheat the oven to 350°F (175°C).
Place the potatoes in a large pot of cold salted water. Make sure all the potatoes are well submerged by at least 2 inches of water. Bring to a boil, then reduce to a simmer and cook for 20-25 minutes or until a sharp knife can easily pierce through them.When they are ready, drain and dice evenly.
While the potatoes are simmering chop the parsley and leeks (thinly sliced). Also, combine the ingredients for the egg mixture (eggs, parsley, salt and pepper). Whisk until well blended. Stir in the grated provolone or mozzarella. Do not overbeat.
Over medium heat, heat the olive oil in a 10-inch nonstick oven-proof pan. You can also use a cast iron pan.
Add the sliced leek and saute for 5 minutes or until softened, stirring occasionally.
Add the diced potatoes; stir gently with the leeks to combine properly together. Season with salt and pepper.
Spread evenly in a single layer and cook 1-2 minutes.
Pour the egg mixture over the leeks and potatoes in the pan and stir gently to combine.
As the mixture begins to set and the bottom firms up, use a spatula or wooden spoon to lift the edge closest to you and allow the uncooked egg mixture to run underneath. Tilt the pan as you do this.
Continue in this fashion until the top is no longer runny and the egg mixture is almost set. It should begin to pull away from the sides.
Sprinkle 2 tablespoons of grated cheese evenly over the top.
Place the pan in the preheated oven.
Bake for about 2-4 minutes until the center is set, dry to the touch and lightly browned.
Let stand a few minutes then run a spatula around the edge and slide gently to a serving plate.
Optional: Garnish with extra parsley, basil or sliced green onions.
Slice into wedges and serve it hot, at room temperature or cold.
Please keep in mind that the nutritional information provided below is just a rough estimate and variations can occur depending on the specific ingredients used.