1 tbsp chicken demi-glace (can be found at williams-sonoma)
40 grams flour
40 grams butter
Mince onion and garlic.
Peel potatoes. Cut them into small, regular pieces. Size/shape is less important than uniformity of size. They need to have the same cooking time.
Cut leeks shortways, creating slices resembling a quarter. Soak these in cold water to rinse.
Prepare the roux. Melt the 40 grams of butter in a pan and add the equal amount of flour. Cook over a low heat for 5 minutes, constantly stirring until it turns into a wet paste (if it turns brown the heat is too high).
Sweat the onion and garlic in a little butter (do not brown).
Once tender, add the chicken stock, cream and potatoes. Simmer until the potatoes are tender.
At this point the soup will be very thin. Add some roux and bring the soup to a boil (a liquid must boil for a roux to take effect). Add more roux and bring to a boil if soup still need thickening.
(Optional) Microwave the chicken demi-glace with a little water in a bowl. Once liquefied, add to soup for flavoring.
Add drained leeks.
Simmer for another 2 minutes. Salt and pepper to taste.
Cut the potato in a rectangle and then cut into squares from there. It wastes potato, but saves time.
This soup will taste better as left-overs over the next few days as the flavors come out over time.