Heat the olive oil in the insert of your slow cooker or frying pan over low heat. Add the leek and garlic and cook for 5-6 minutes, or until softened.

Return the insert pan, if using, to the slow cooker, or transfer the leek mixture to the slow cooker. Add the stock and potatoes. Cover and cook on high for 3 hours, or until the potato is very tender.

Near serving time, fry the bacon pieces in a frying pan until crispy.

Add the milk or cream to the slow cooker. Pure the mixture until smooth, using a hand-held stick blender or food processor. Season to taste with sea salt and freshly ground black pepper.

Ladle into bowls and top with the bacon bits.