Broccoli and Stilton Soup

Ingredients

• 2 tbsp rapeseed oil
• 1 onion, finely chopped
• 1 stick celery, sliced
• 1 leek, sliced
• 1 medium potato, diced
• 1 knob butter
• 1 litre low salt or homemade chicken or vegetable stock
• 1 head broccoli, roughly chopped
• 140g stilton, or other blue cheese, crumbled