Heat a large skillet over medium-high heat. Brown the ground beef, breaking it into crumbles as it cooks. Drain any excess grease if needed.

Add the diced onion and garlic to the skillet and cook for 2 minutes, until softened and fragrant. Transfer everything to the slow cooker.

Stir in the marinara sauce, crushed tomatoes, Italian seasoning, brown sugar, cayenne pepper, bay leaf, salt, and black pepper until well combined.

Cover and cook on LOW for 6–8 hours or HIGH for 3–4 hours.

About 10 minutes before serving, cook the gnocchi according to the package directions. Once the gnocchi float to the surface, drain well.

Remove the bay leaf, then gently fold the cooked gnocchi into the meat sauce until evenly coated.

Serve topped with freshly grated Parmesan cheese and chopped fresh parsley or basil, if desired.