In a frying pan, cook your bacon. Drain it on a serviette then cut it into bits. Melt butter on medium high heat then add in your potatoes, leeks and onions.
Sauté for a bit (about 5 minutes) until it smells good. Add bacon, chicken stock, white pepper, bay leaf and marjoram then cover and simmer until veggies are tender (about 30 minutes). Mix flour with a wee bit of water then stir into soup. Simmer for 10 more minutes uncovered.
Mush it up with a potato masher, add cream then taste. Add salt if needed then serve in with cheese toasties or mouse traps.