Step 1

Cook the tagliatelle in a large saucepan of boiling salted water according to packet instructions, then drain.

Step 2

Meanwhile, melt the butter in a deep frypan over medium heat. Add bacon and cook until beginning to crisp. Add the garlic, rosemary and mushrooms and cook, stirring occasionally, for a further 5-6 minutes. Add the creme fraiche and grated cheese and stir for 2 minutes, then add three quarters of the toasted walnuts. Add the drained pasta and parsley to the sauce, tossing together until heated through. Divide among serving bowls, then sprinkle with remaining nuts and extra cheese.