Lightly spray the bowl of a slow cooker with cooking spray.

Place the cauliflower in the slow cooker. Pour the milk and chicken broth over the cauliflower. Add the garlic powder, sea salt, and black pepper.

Cover and cook on HIGH for 2 hours, or until the cauliflower is tender.

In a small bowl, mix the cheddar and mozzarella cheese.

Add the cheese to the cauliflower mixture and cook on HIGH for 30 minutes. Sprinkle the cauliflower with the crumbled cooked sausage and cook for another 30 minutes.

Garnish with the green onions. Serve immediately.