Pre heat the oven to 425ºF / 220ºc.
Break the cauliflower into florets and place on a foil lined baking sheet. Add 2 tablespoons of oil and a couple of generous pinches of salt and pepper and mix with your hands so the cauliflower is evenly coated.
Roast the cauliflower in the oven for about 35 to 40 minutes until it is soft and browned.
While the cauliflower is roasting, you can get on with the rest of the recipe.
In a heavy bottomed pan, melt the butter over a high heat and fry the bacon until it is crispy. Remove the bacon, leaving the fat in the pan, and set to one side. Leave the pot on the heat and turn down to a medium heat.
Add the onion, garlic and salt and pepper to the pot and cook for 5 to 10 minutes until softened.
Add the cream, stock, blue cheese and roasted cauliflower and bring the pot to the boil. Stir occasionally until the cheese has all melted.
Use an immersion or stand blender to blend the soup until it is smooth and creamy.
Taste and season to taste if needed.
Serve with the crispy bacon pieces.