In a pan over medium heat, cook the bacon until golden but not crispy, around 5 minutes.
Place the bacon in paper towels. Discard the bacon fat.
In the same pan, melt the butter and sauté the onion and celery until tender, 6-8 minutes.
In the mean time, put the potatoes and the water to boil.
Once they boil, add the sautéed onion and celery. Reduce the heat and boil for 20 minutes, semi covered.
With an immersion blender, blend all the ingredients until creamy, being careful not to over blend.
Add the milk and the bacon.
Simmer for 10 minutes.
Add half of the cheddar cheese and stir.
Add salt and pepper to taste.
Serve and garnish with cheese and ciboulette.