Cook the bacon pieces in a heavy skillet over medium heat until they are brown
. Remove, set aside. Add olive oil to the bacon greased pan and add onion and cook until tender. Put bacon back on.
In a separate bowl mix parsley, ricotta, prosciutto and egg yolks. Cook the spaghetti the way you like it. Drain. In a large bowl toss the noodles with the parsley, cheese-prosciutto mixture. Pour on the onion-bacon mix. Sprinkle grated parm on top. :o)