Meanwhile peel and cut the onion, cellery sticks and white of the leek and weigh them out. Cut: onions in 1/4 inch by 1/4 inch, leek in rings and cellery in 1/10 of an inch slices. Cellery leaves can be included.
Also peel and cut the potatoes in 1/5 x 1/5 inch (5 mm x5 mm) cubes.
Boil the cut potatoes in 300 ml of the clam broth for 10 minutes. Right thereafter, scoop half of the potatoes out with a slotted spoon and reserve in a separate bowl. Leave the rest in a separate bowl or pan and reserve.
Meanwhile in a large enough pan, fry the slices of bacon on both sides until rather crispy (5 min) Take the slices of bacon out let cool down and reserve.
To the pan with the bacon fat, add first the onions and fry at high fire for 1-2 minutes, thereafter add the sliced garlic, the sliced leeks and the sliced cellery, each with a minute in between. Then reduce the heat to low and let the whole mixture become glazy or golden in color (15-20 min). Watch and mix regularly. Do not let the vegetables get dark brown.
After 20 minutes, add 1 tbsp of brandy and scrap the pan with a wooden spatula and mix the contents. (1 min)
Then add the one part of the cooked potatoes with their cooking fluids and the remainder of the broth to the smothered vegetables, add the thyme, bay leave and bring to a simmer. Simmer for 20 minutes
Then use an immersion blender to homogenize the soup
Taste the soup. Usually there is no need to add additional salt.
Add the other part of the cooked potatoes, add now diced parsley (optional) stir and let stand for 10 minutes.
Before serving, add 1 tbsp of the cream to each bowl and decorate the soup with bacon and sliced scallions (optional) on top.