Cook the pasta in plenty of salted water until al dente. Preheat the oven to 200 ° C. Cut the leek into slices, halve the mushrooms and also cut into slices. Put the corn in a colander and drain. Halve the chicken breast lengthways and cut into 1 cm thick slices.
Fry the chicken breast in oil until it gets color, then add the leeks and mushrooms and fry for 2-3 minutes. Add flour and fry briefly. Add the cream, milk, cream cheese and 3 tablespoons of grated cheese. Simmer for 2-3 minutes, season with salt, pepper, nutmeg, cayenne pepper and garlic powder.
Mix the corn and macaroni with the mixture and place in a baking dish, spread the remaining cheese on top and sprinkle with breadcrumbs. Put the butter flakes on top and bake in the oven for about 30 minutes.