Heat the oil. Fry the garlic and walnuts in it. Add milk and gorgonzola and bring to a boil. Stir until the cheese has melted.
At the same time bring plenty of water to the boil for the pasta, add salt. Cook the pasta al dente in it.
Mix the sauce with the diced tomatoes, season with salt and pepper and add some cooking water if necessary. Mix with the drained pasta and serve immediately.