In a large skillet, heat the avocado oil over medium heat. Add the onion and sauté until the onion is soft and translucent, add garlic and cook for another minute.
Add the ground beef and cook until browned, breaking it up as you go.
Transfer the beef mixture to your slow cooker.
Add crushed tomatoes, tomato paste, oregano, basil, salt, pepper, Worcestershire sauce, a bay leaf, brown sugar, water, and bouillon. Stir it all together.
Cover and cook on low for 6–8 hours or high for 3–4 hours.
About 20 minutes before you’re ready to eat, boil your pasta.
Toss the bay leaf, then serve the sauce over the pasta with a shower of grated Parmesan on top.