Remove any tough or wilted outer leaves. Cut the cabbage into quarters and remove the core. Chop into bite-sized pieces.
Add chopped cabbage to the slow cooker. Pour in vegetable broth and apple cider vinegar. Sprinkle it with garlic powder, smoked paprika, salt, and pepper. Gently stir to distribute seasoning and combine.
Dot the top of the cabbage with cubes of butter. Do not stir after adding.
Cover and cook on high for 2–3 hours or low for 4–6 hours, until cabbage is tender. Stir once midway through cooking and add extra broth if needed.
Give the cabbage a final stir before serving. Adjust seasoning to taste.
Notes
Cabbage releases moisture as it cooks, but feel free to add more broth if you prefer it very soft or saucy.
Stir in sliced onion or shredded carrots at the beginning for extra flavor and texture.
Add red pepper flakes for a touch of spice.
For deeper flavor, add ¼ to ½ teaspoon liquid smoke with the broth.