Heat a large skillet over medium-high heat with oil.

Add the diced potatoes and let them brown for 9-10 minutes, stirring occasionally.

Add a large splash of water to the pan, cover with a lid or a piece of foil and let the potatoes cook through, about 3-4 minutes, shaking the pan occasionally.

To a mixing bowl, add eggs, milk, Parmigiano-Reggiano, salt, pepper, and garlic powder. Whisk to combine.

Once the potatoes are cooked through, pour the egg mixture over the potatoes and let it set for about 20 seconds.

Using a spatula, scramble the eggs into large curds, without breaking the potatoes.

Serve potato and egg mixture on rolls with ketchup.

*If packing for lunch, let the eggs cool, stuff the rolls with potato and egg mixture, top with ketchup and wrap tightly in foil. Reheat in a toast oven!