Remove the core from the cabbage, keeping the leaves intact so they can soak up all the flavors.
In a small saucepan over low heat, melt the butter. Add the minced garlic and cook until fragrant, about 1-2 minutes.
Remove from heat and stir in the Parmesan cheese, lemon zest, and lemon juice.
Place the whole cabbage in the slow cooker. Pour the garlic-Parmesan-lemon butter mixture evenly over the cabbage, making sure some seeps between the leaves.
Sprinkle the cabbage with salt and black pepper.
Pour the vegetable broth around the cabbage in the slow cooker.
Cover and cook on low for 6-8 hours, until the cabbage is tender and infused with the garlic and lemon flavors.
Carefully transfer the cabbage to a serving plate.
Garnish with freshly chopped parsley and serve warm.
Enjoy!