Heat the olive oil in a large frying pan and sizzle the pancetta or bacon for about 5 mins until starting to crisp. Turn up the heat and add the grated courgette to the pan. Cook for 5 mins or until soft and starting to brown then add the garlic and cook for a minute longer. Season and set aside.
Cook the tagliatelle according to the pack instructions and scoop out a cupful of cooking water. Drain the tagliatelle and tip into the frying pan with the bacon and courgette. Over a low heat toss everything together with the crème fraiche and half the Parmesan adding a splash of pasta water too if you need to loosen the sauce. Season to taste and serve twirled into bowls with the remaining Parmesan scattered over.