Fry the hazelnuts in a pan without fat until golden brown and remove them. Clean, wash and cut the leek into rings. Peel garlic and chop finely. Cut bacon into pieces and drain in a hot pan without fat. Take out and drain on kitchen paper.
Cook the pasta in boiling salted water for about 10 minutes. In the meantime add butter to the frying fat, fry leek and garlic in it. Dust with flour and sauté briefly. Deglaze with milk, stir in broth. Let simmer for about 10 minutes. Drain the pasta and let it drain. Take sauce from the stove and stir in processed cheese. Season sauce with salt, pepper and lemon juice. Arrange noodles and the leek-cheese sauce in bowls.
Let simmer for about 10 minutes. Drain the pasta and let it drain. Take sauce from the stove and stir in processed cheese. Season sauce with salt, pepper and lemon juice. Arrange noodles and the leek-cheese sauce in bowls. Sprinkle with crispy bacon and roasted hazelnut leaves