Leek and Cheese Soup

45ml butter
15ml vegetable oil
2 large leeks, sliced
2 onions, chopped
2 cloves of garlic, minced
600g potato, peeled and diced
2litres chicken stock
5ml salt
black pepper
200g mature cheddar cheese, grated
80g cheese and onion potato chips

Add the butter and oil to a large saucepan set over medium-high heat.
Add the leeks and onion and cook while stirring until completely wilted and soft.
Add the garlic and cook for another minute.
Add the diced potato, stock, salt and pepper and bring the mixture to a simmer.
Lower the heat to a slow simmer, cover the saucepan with a lid and cook for about 30 minutes. Check on the soup every now and then and adjust the heat as you go. The potato must be very soft.
Decant the soup into a blender and blitz together until smooth and silky.
Pour the soup back into the saucepan and place over a low heat.
Add the grated cheese and stir the soup until the cheese has melted.
Spoon the soup into individual bowls.
Crush the potato chips in the packet and sprinkle a generous amount onto each bowl of soup.
Serve immediately.