Remove harder leaves from the spring onions. Remove the roots from the leeks and, rinse and finely slice them separately. Rinse and dry the chicken breast; heat the oil in the pan, add the chicken breast, season with salt and pepper, golden on both sides and cook for about 8 minutes.Drain it then place it in a plate and cover it with a dish to keep it warm. In the same pan add the leeks and fry until soft; pour the white wine and 3 tbsp of water and cook for 10 minutes. Add the spring onions and continue cooking for an additional 10 minutes.Pour a glass of water and continue cooking for another 10 minutes, stirring from time to time with a wooden spoon. Season with salt and pepper. When ready put the mix in a mortar, preferably milled, or in a food processor and blast until it reaches a smooth sauce. In the meanwhile cook the pasta in plenty of boiling water.Drain it then put it in a preheated deep serving dish, and constantly stirring, add the parmesan and a dash of oil. Place the strips of chicken breast and the warm sauce; serve immediately.