Boil the spaghetti according to package directions.
In a large pot or dutch oven over medium heat, add the olive oil. Once hot add the onion and saute for 5 minutes or until the onion is soft.
Add the chicken broth in and scrape the bottom of the pot, add the rest of the ingredients in, stir to combine. Simmer covered for 15 minutes (stir frequently) then uncovered for 5 minutes. You can serve as it is now but normally I like to place this mixture in my blender to make it completely smooth. Serve over the noodles.