Place potatoes in a saucepan of water and bring to the boil, simmer for 5-6 minutes, or until potatoes are just cooked through.
Meanwhile, heat the olive oil in a medium sized non-stick pan and fry the onion over a medium heat until softened. When the potatoes are cooked, drain and add to the pan with the onions.
In a large jug season the eggs and milk with Salt and Pepper add the Garlic Granules, Parsley and Crushed Chilles (if using) and lightly beat together.
Pour the egg mixture into the pan with the potatoes and onion. Stir continuously until the eggs begin to set, allow to continue to cook in the pan for 4-5 minutes, after which time the tortilla will be cooked on the bottom, but still slightly runny on the top. Finish under a hot grill for a further 2 minutes or until completely set.
Using a flexible spatula carefully loosen the sides of the pan, then slide out onto a plate. Sprinkle with the Smoked Paprika to finish then cut into squares and serve.