Place the chicken in a large pot with 5 teaspoons kosher salt, 2 bay leaves, and 1 head of garlic. Cover with 12 to 16 cups water or enough to submerge the chicken. Bring to a boil. Reduce the heat to low and cover. Simmer for 1 hour 30 minutes or until the chicken is cooked through. Periodically skim the surface to remove foam and scum from the top of the broth.

Carefully transfer the chicken to a large bowl. Remove the head of garlic and transfer it to a small bowl. Return the pot of broth to a rapid simmer over medium heat. Simmer, uncovered, for about 20 minutes to reduce the liquid and concentrate the flavors.

Pour the broth into a large bowl through a fine-mesh sieve. Discard the solids and wipe out the pot. You should have 8 to 10 cups broth.

Once the chicken is cool enough to handle, pick the meat from the bones and shred it with your fingers or roughly chop it with a knife. Reserve the skin and bones to make stock if you like.

Carefully pop the garlic cloves from their skin and mash the cloves into a paste. Set aside.

Heat 1 tablespoon extra virgin olive oil in the pot over medium heat. Add the sliced leek, onion, and celery. Sauté for 6 to 8 minutes until fragrant.

Add the potatoes and season with 1½ teaspoons kosher salt and 1 teaspoon black pepper.

Pour the prepared broth into the pot and bring to a boil. Reduce the heat to low and stir in the shredded chicken and mashed garlic. Simmer, uncovered, for 30 minutes or until the potatoes are fork-tender. Taste and adjust the seasonings to your preference.

Add the frozen peas, chopped dill, chopped tarragon, and half the lemon juice. Simmer for 5 minutes.

Whisk together the crème fraîche and the rest of the lemon juice. Add a pinch of flaky sea salt. Sprinkle a few dill sprigs on top and set aside.

Ladle the soup into bowls and spoon créme fraîche on top of each bowl. Enjoy!