Peel the leaves from the cauliflower and cut into medium florets. Place in your slow cooker and top with garlic cloves, vegetable broth, and enough water to cover the cauliflower. Cook on low heat for 6 hours or high heat for 3. Drain the water and broth and add the cauliflower back to the slow cooker. Toss in the butter and use an immersion blender or hand blender to mash. Season with salt to your taste and mix in fresh herbs. Set on keep warm until ready to serve.