Peel the shrimps, except for the tail fin, and put the shell aside. Remove the intestines. Wash shrimps and pat dry. Heat 1 tablespoon of oil in a saucepan. Sauté half of the shells in it for 3-4 minutes, then deglaze with cider.
Season with salt and pepper and simmer for about 20 minutes at low heat. Pass the liquid through a sieve, squeezing the peels well.
Clean and wash the leek, removing the upper green part. Cut the leek into fine strips. Melt 10 g butter in a pan. Steam the leek for 4-5 minutes until the strips are soft.
Cut white sausages into slices (4-5 mm thick). Heat 1 tablespoon of oil in a frying pan. Fry the sausage slices for about 5 minutes while turning. Remove and fry the scampi in the pan for approx. 4 minutes.
Season with salt and pepper. Mix the scampi, white sausage and leek.
Put the scampi stock and 50 g butter in a pot and simmer for about 5 minutes. Season the sauce with salt and pepper and blender briefly. Put the white sausage mix in the
Arrange in bowls and serve.