Cream of clams with mussels:
Wash and scrub the mussels. Discard any that appear suspicious (open or broken).
Put them in a large pot and cook for 5 minutes or until they are open.
Let them cool slightly before shelling. Filter the mussel juice and set aside.

In a saucepan, bring the cream, milk, chicken broth, clam juice, and mussel juice to a boil.

In a bowl, prepare a kneaded butter by mixing the butter and flour with a fork.
Add it to the milk with a whisk.
Add the wine, thyme, and season with salt and pepper to taste.

Meanwhile, in a pan, heat the butter and sauté the mushrooms, leek, and celery for 5 to 7 minutes.

Add the vegetable preparation, mussels, and clams to the cream.
Serve in hollow bowls with a few drops of parsley oil and a brown butter crouton.

Brown butter croutons:
In a thick-bottomed saucepan, melt the butter slowly.
Stir and wait about 5 minutes for it to take on a beautiful brown color (and smell like hazelnuts).
Stop cooking by plunging the bottom of the saucepan into a bath of cold water.
Dip the croutons in the brown butter and place them on a cookie sheet.
Season the croutons with salt and pepper to taste, then place them under the broiler for a few minutes.

Parsley oil:
Using a food processor, pulse the parsley and oil for a good minute.
Filter and bottle.