Prepare the pasta in boiling salted water according to the instructions on the packet. Peel onions and cut into strips. Wash sage, shake dry, pluck leaves from the stems. Leave bacon in a pan without fat until crispy.
Remove the bacon slices. Sauté onions and sage in the bacon fat for about 5 minutes. Add olives. Slice parmesan. Drain the pasta in a sieve, collecting about 1/4 litre of cooking water. Pour cooking water into the pan and bring to the boil.
Put the pasta back in the pot. Add sauce and bacon and fold in. Serve with ricotta stains on plates. Sprinkle with parmesan and season with salt and pepper.