Melt the butter in a thick-based saucepan, then add the prepared vegetables and some salt, and cook gently with the lid on for 5-10 minutes to draw out the juices.
Stir in the cornflour to absorb the juices and, when smooth, gradually pour in the cider – still stirring.
Add the chicken or vegetable stock, cover the pan and simmer gently for 30 minutes.
Then add the milk and Stilton and re-heat, stirring, until the cheese has melted and the soup is just below boiling point.
Taste and season with salt and pepper, then stir in the creme fraiche.
At this stage you can purée the soup in a food processor or with a hand held blender or, if you prefer the texture of the chopped vegetables, keep it as it is.
Serve the soup with the Parmesan croutons & the chopped chives.
Pre-heat the oven to gas mark 4/180C/350F or pre-heat the grill.
Place the bread cubes in a bowl, sprinkle in the oil, then stir them around until the bread has soaked up all the oil.
Next add the freshly grated Parmesan, and stir again till all the bread cubes are well coated.
Spread them out over a baking sheet and either bake in the pre-heated oven for 10 minutes, or else place them under the pre-heated grill, turning as necessary. (If you use the grill, watch them VERY CAREFULLY as they can burn very easily.).
The croutons can be made well in advance and stored in an airtight tin for up to two weeks.