While the Lyonnais didn't invent macaroni, this pasta became one of the first popular in France during the 19th century. Lyonnaise cuisine embraced it wholeheartedly.
Begin by making a classic béchamel sauce: Melt 50 g butter with the flour over low heat, then whisk in the milk. Simmer gently, stirring constantly. Season with salt, pepper, and a grating of nutmeg.
Cook the macaroni in abundant boiling salted water for about 15 minutes until al dente. Coarsely grate the Beaufort cheese.
Drain the pasta. Warm the béchamel, stir in the fresh cream and 3/4 of the cheese. Preheat oven to 210°C.
Butter a gratin dish. Layer macaroni and cheese béchamel alternately. Top with remaining sauce and grated cheese.
Bake until golden, about 20 minutes. Serve hot from the dish.
