Method
1. Heat butter and sunflower oil to a clean large cast iron skillet
2. Add leek, bacon and potato
3. Fry until light golden - medium heat
4. Add vegetable stock, salt and pepper
5. Bring to boil
6. Transfer content of large cast iron skillet to slow cooker bowl
7. Cook - 5 hr 30 min, low heat
8. Stir in milk to the soup
9. Add bacon to a clean baking pan
10. Broil in broiler until crispy
11. Cut into pieces then set aside
12. Purée soup with stick blender
13. Add heavy cream and stilton cheese to the soup
14. Transfer bacon to soup
15. Season to taste
16. Sprinkle with stilton cheese and serve