Melt the butter in a pan, add the onion and fry until soft.
Add the cauliflower, stock, bouquet garni and salt and pepper to taste. Bring to the boil, cover and simmer for 15 minutes; cool slightly. Remove the bouquet garni.
Sieve or process in an electric blender until smooth.
Blend in the cornflour with 2 tbsp of the milk. Add to the purée with the remaining milk. Bring to the boil again, stirring.
Remove from the heat, and stir in the cheese. Pour into warmed individual soup bowls and garnish with parsley. Serve immediately.
I have written it here as it appeared in my cookbook but the first time I made it, I tasted it before finishing it off, and added more stilton (I used 6oz of stilton in total) and it tasted even better. Try serving it with some hot garlic bread. This recipe makes a large quantity but you can cool and freeze what you don't want to use immediately.