In a large mixing bowl, combine the Italian sausage, ground beef, egg, crushed pork rinds, Italian seasoning, basil, Parmesan cheese, and all-purpose seasoning. Mix just until combined.

Shape the mixture into approximately 2-inch meatballs.

Heat the olive oil in a large skillet over medium-high heat. Brown the meatballs on all sides, then transfer them to the slow cooker.

Melt the butter in the same skillet. Add the onion and cook until softened, about 4 to 5 minutes. Stir in the garlic and cook for 30 seconds.

Add the crushed tomatoes, beef broth, basil, oregano, rosemary, and confectioners' sugar. Stir until combined and bring to a gentle simmer.

Pour the sauce over the meatballs in the slow cooker.

Cover and cook on High for 3 hours or Low for 5 to 6 hours, until the meatballs reach an internal temperature of 165 degrees F.

Serve over cooked spaghetti or with your favorite pasta.