Peel and slice the potatoes. Clean and wash the spring onions and cut the white and light green diagonally into 2 cm wide rings. Finely dice the garlic. Pluck the parsley leaves from the stems, put some leaves aside, finely chop the remaining leaves.
Season the eggs in a bowl with parsley, salt and pepper and whisk well.
Heat 2 tablespoons of oil in an ovenproof, coated pan (26 cm diameter). Sauté the potatoes and garlic over a medium heat for approx. 13 minutes, turning occasionally, and season with salt and pepper. Add the spring onions, cook for another 3 minutes and remove from the pan.
Heat 2 tablespoons of oil. Fry the prawns for 3 minutes while turning, then remove half of the prawns from the pan. Add the potatoes and spring onions and stir. Add the eggs and cover and let stand for 3-4 minutes over a mild heat.
Bake the tortilla open in the preheated oven at 180 ° C on the 2nd rack from the bottom for 10-15 minutes. Take the tortilla out of the oven and carefully slide it onto a plate, cover with the remaining prawns and garnish with parsley leaves.