Bring a large pot of water to a boil and carefully place the whole head of cabbage into the water. Boil for 8-10 minutes until the outer leaves become pliable and translucent. Using tongs or a slotted spoon, carefully peel away the softened leaves one at a time and set them aside on a clean kitchen towel. Return the cabbage to the water and repeat this process until you have 12-14 usable leaves. Pat the leaves dry gently with the towel to remove excess water, which helps them roll more easily without tearing.

In a large mixing bowl, combine the ground beef, mild Italian sausage, uncooked rice, minced garlic, onion powder, salt, cracked black pepper, and smoked paprika. Crack the egg into the mixture and stir everything together until just combined—avoid overmixing, which can make the rolls tough. I like to use my hands for this to ensure the egg and seasonings are evenly distributed throughout the meat and rice, which gives you more consistent seasoning in each bite.

Place a cabbage leaf on a clean surface with the smoother side down. Scoop approximately 3-4 tablespoons of the filling mixture from Step 2 onto the center of each leaf. Fold the sides of the leaf inward, then roll tightly from the base toward the tip, creating a compact packet that keeps the filling enclosed. Work gently to avoid tearing the leaves—if a leaf tears, use it as a wrapper layer on the outside of another roll. Arrange the completed rolls seam-side down on a plate until ready to transfer to the slow cooker.

In a medium bowl, whisk together the tomato sauce, granulated sugar, beef base (Better Than Bouillon), and Worcestershire sauce until the beef base is fully dissolved and the sauce is smooth. This creates a rich, savory liquid that will cook with the rolls. Pour about one-third of this sauce mixture into the bottom of your slow cooker, then arrange 6-7 cabbage rolls from Step 3 seam-side down in a single layer. Pour half of the remaining sauce over these rolls, then layer the second batch of 6-7 rolls on top and cover with the rest of the sauce. This layering approach ensures even sauce distribution and prevents the bottom rolls from drying out.

Cover the slow cooker and cook on HIGH for 3-4 hours. The rolls are done when the rice is tender and the internal temperature of the filling reaches 165°F when checked with an instant-read thermometer. I find that checking around the 3-hour mark helps prevent overcooking—the longer these cook, the softer the cabbage leaves become, which is wonderful for texture but can fall apart if overdone. Transfer the rolls to a serving platter and spoon the sauce from the slow cooker generously over them, then garnish with the fresh chopped parsley.