Remove meat from cooked lobsters and reserve shells.

Stud onion all over with whole cloves.

Break up lobster shells and place in soup kettle with water, onion, celery, and bay leaf.

Simmer for 45 minutes to create a flavorful broth.

While the broth is simmering, soften the butter at room temperature.

Mix lemon extract into softened butter and refrigerate until ready to serve.

Strain the broth through a sieve into a clean soup pot to remove solids.

Add lobster meat and sherry to the strained broth.

Season the soup to taste with salt, pepper, cayenne, and nutmeg.

Bring the broth back to a simmer over low heat until the lobster is heated through.

In a small bowl, beat the egg yolk.

Whisk the heavy cream and 1/2 cup of the soup broth into the beaten egg yolk to temper the egg.

Pour the cream mixture gradually into the remaining soup mixture and heat for 1-2 minutes longer, being careful not to boil.

Pour the bisque into soup bowls and top each with 1/2 tablespoon of lemon butter.

Garnish with fresh chopped parsley and serve immediately.