Prep the cabbage. Remove any wilted outer leaves.
Cut the cabbage into quarters, remove the core, and slice into thick shreds or wedges about 1–1.5 inches wide. Thicker pieces hold up better in the slow cooker.
Layer the vegetables. Add the sliced onion and garlic to the bottom of the slow cooker. Place the cabbage on top.
This helps the flavors distribute as the cabbage cooks down.
Season generously. Sprinkle in the salt, pepper, and smoked paprika (if using). Dot with butter or drizzle with olive oil. Pour the broth around the edges so it reaches the bottom.
Cook low and slow. Cover and cook on LOW for 5–6 hours, or on HIGH for 2.5–3 hours, until the cabbage is very tender but not falling apart.
Give it a gentle stir once midway if you can.
Finish with acidity. When it’s done, stir in the apple cider vinegar or lemon juice. This brightens the flavor and balances the richness.
Taste and adjust. Add more salt, pepper, or red pepper flakes to taste. Garnish with parsley if you like.
Serve warm.