Thoroughly clean the sand from clams. Put them in a deep pot. Add 4 glasses of cold water and close the lid. When the water starts to boil, lower the heat and cook until the clams open. (about 8-10 min)
Remove the cooked clams from the water with the help of a strainer on a tray.
Pour the water in which you boiled the clams through a fine strainer into a deep bowl. Completely remove sand.
After washing and drying the pot, put it back on the stove and switch on the heat. Put the butter into the heated pot and melt it. Add the chopped bacon and cook in the butter until crisp, about 10 minutes. Place the cooked bacon on a plate covered with paper towel.
Add the chopped onion and celery to the remaining oil in the pan. Cook for about 8 minutes until soft. Add 6 glasses of the reserved clam boiling water, potatoes, thyme and bay leaves to the vegetables and mix.
Bring to a boil and reduce the heat. Cook for about 20 minutes until the potatoes are soften. In a small cup, mix the starch with 2 tablespoons of cold water to make a slurry. Stir the starch mixture into your soup. From this point on, stir constantly until it boils.
Once the soup has thickened, stir in the clams, 3/4 of the fried bacon and the heavy cream.
Ladle the soup into bowls and garnish with the remaining bacon and oyster crackers if desired.
Clam chowder is ready to serve. Bon Appetit!