Fry the bacon in a large pot until crispy. Remove the bacon and set aside, leaving the fat in the pot.

Melt the butter in the pot with the bacon fat. Add the onion and cook until softened.

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

Carefully blend the soup using an immersion blender or transfer to a regular blender. Blend until smooth.

Stir in the heavy cream and season with salt and pepper to taste.

Serve immediately, garnished with the crispy bacon.