Melt butter in a large pot over medium heat.

Add cauliflower florets and vegetable broth to the pot. Bring to a boil, then reduce heat and simmer for 20-25 minutes, or until cauliflower is tender.

Carefully transfer the soup to a blender (or use an immersion blender) and blend until smooth and creamy.

Return the soup to the pot and stir in heavy cream, salt, and pepper.

Heat through and serve.