Heat a medium dutch oven over medium heat.
Dice the onion, carrot, celery and mushrooms super small. This will help them cook faster and help deepen the flavor as it cooks.
Dice the bacon into small pieces and cook until mostly done – you want it to be somewhere between mostly limp and mostly crispy. Remove the bacon from the pan, but keep the drippings.
Add the onion, carrot, celery and mushrooms to the dutch oven and cook, stirring frequently, for 3-5 minutes, or until the onion is starting to become translucent.
Add in the ground beef and cook for 10 minutes, stirring occasionally, until there is no more pink left. Drain off any accumulated grease.
Add in the garlic and Italian seasoning.
Stir in the diced tomatoes, tomato sauce, beef broth, tomato paste, and bay leaf.
Bring to a boil, then allow to simmer for 10-15 minutes.
Remove the bay leaf, and serve over pasta with freshly grated tomato cheese and fresh chopped parsley.