Halve the leek, halve lengthways and cut into thin strips, sauté with butter. Cut the cheese into pieces, add and let melt.
When the cheese has melted, deglaze with milk, wine and cream and let it simmer for a while. Squeeze in the garlic and season with pepper, salt, granulated broth and sugar.
If the sauce is too runny, you can thicken it a little with a binding agent. Cook the pasta in salted water until al dente and serve with the sauce. A crunchy salad should be enough with it.