Core the chili peppers and cut into strips. Cut the onions into strips and the garlic into slices. Heat the butter and olive oil, sauté the chilli, onions and garlic in them. Cook the pasta until al dente, drain and drain well. Grate half of the walnuts, stir into the onion mixture with the pine nuts and basil. Season with salt and pepper. Mix the tagliatelle with the sauce, garnish with the remaining nuts and sprinkle with parmesan.