Heat 2 tablespoons of Olive oil in a large saucepan over a low-medium heat. Add the 1 Onion (diced) and cook for 3 minutes until it is starting to soften.
Add 1 rib of Celery and 270 g of Potato (both diced) cook for another 4 minutes, stirring occasionally.
Add 300 g of Broccoli and 1 litre of Vegetable stock (low salt).
Bring to a gentle simmer and cook for around 15 minutes, or until the potato and broccoli are tender.
Avoid boiling the broccoli for longer than necessary, as overcooking it can dull the colour and flavour.
Remove the pan from the heat and crumble in 100 g of Stilton.
Stir for a few seconds to allow the cheese to start melting.
Use a stick blender to blend the soup until smooth.
Taste before adding any extra salt, as both the stock and Stilton can already be quite salty. Add plenty of freshly ground black pepper and adjust the thickness with a little extra hot stock if needed.
Notes
Use the broccoli stalk as well as the florets rather than throwing it away.
Keep the broccoli cooking time as short as possible once tender to help retain its colour.
Remove the soup from the heat before adding the Stilton.
Taste before adding salt, as Stilton and stock can both be salty.
Add extra stock after blending if you want a thinner consistency.
Use a stick blender for the easiest and safest blending.
Use lower-salt stock if serving to children.
Reheat the finished soup gently rather than bringing it to a vigorous boil.