of the butter and all of the chicken livers to the skillet. Sauté until
the exteriors are brown—3 to 4 minutes—and then season with
salt, pepper, the thyme, and, if you’re using it, the sage. Cook for
another minute until the livers are lightly caramelized but still pink
inside.
Remove the skillet from the heat and add the port. Return the
skillet to medium-high heat and deglaze it by scraping up the
brown bits with a wooden spoon. Bring the liquid to a boil and
continue to cook until it has reduced to 2 tablespoons. Pour into
the food processor. Process the mixture until it’s very smooth and
then scrape the mixture into a fine-mesh sieve. Using a rubber
spatula, push the puree through the sieve into a separate bowl.
Let the mixture cool almost to room temperature, and then
whisk in the final 3 tablespoons of butter and the lemon juice*;
taste and season with salt and pepper.
Line a bowl with plastic wrap and transfer the liver puree to
that bowl. Cover and chill for at least 3 hours or overnight.
The next day, you can unmold it and serve it with Breton
crackers or, if you’d like, you can stuff it into Cognac-soaked
prunes*. To do that, place the Cognac in a small pan, bring to a
simmer, and add the prunes. Cook for 15 to 20 minutes, until the
prunes have absorbed the liquid. Turn off the heat, allow to cool,
and then cut open each prune and fill it with some mousse. Try
not to eat them all before serving.
* Warning: the chicken livers may spit as they cook.