In a frying pan over medium heat, cook the onions and the bacon with the olive oil until the onions are translucent. Add the wine. Lower the heat and lte it cook for a couple of minutes.
Meanwhile in a large pan, boil the water with salt. Cook the pasta al dente - 8 minutes.
Reserve 1 cup of the cooking water and drain the fettuccine.
Immediately add the pasta to the egg mixture and mix well until all the pasta is coated. Add the bacon - onion - wine mixture and stir until all blended. If too dry, add some of the cooking water.
Serve hot with more Parmigiano.