Place the bacon in a large pan over medium high heat. Cook for 5-6 minutes, stirring occasionally, until bacon is crispy.
Remove the bacon from the pan and place on paper towels to drain.
Spoon off some of the excess bacon grease in the pan, leaving about 1 tablespoon in the pan.
Add the ground beef to the pan. Season with salt and pepper.
Cook, breaking up the meat with a spatula into small pieces, for 4-5 minutes.
Add the onion and carrot to the pan. Cook for an additional 4-5 minutes or until vegetables have softened.
Add the garlic and Italian seasoning, then cook for 30 seconds. If you're using beef with a higher fat content than 90% lean, you'll want to drain off any excess grease.
Place the bacon and beef and vegetable mixture in a slow cooker (at least 4 quart size).
Pour in the jar of marinara sauce and tomato sauce. Stir until everything is well combined.
Cover the slow cooker. Cook on low for 4-6 hours.
Uncover the slow cooker and give the sauce a stir. Sprinkle with parsley, then serve.