Preheat the oven to 180°C.
Wash the potatoes and dry well, then prick each one with a fork and wrap in tin foil. Put on a rack in the middle of the oven and cook for about an hour and 15 minutes. The exact time depends on the size of the potatoes, but they should be soft when ready. Remove from the oven, allow to cool slightly, then cut in half. Set aside and leave to cool fully. Once fully cooled, scoop out the potato flesh and cut into cubes.
Cook the bacon strips in a large pan for 3-4 minutes until cooked. Remove from pan and set aside. In the same pan heat the Stork Margarine. Add the onion and cook for 6-8 minutes on medium heat, until softened but not brown. Add the flour and stir well for 1 minute. Add the milk and Knorr Vegetable Stock Pot and whisk in well. Add the potatoes and black pepper. Bring to the boil then simmer on medium heat for 12-15 minutes until the soup starts to thicken. Remove from heat.
Purée the soup until smooth with a stick blender. Return to the pan to reheat. Adjust the consistency with some extra milk, if it is too thick. Serve topped with grated cheese, bacon strips, a dollop of sour cream and some chopped chives.