Once canned, some of the foie gras as well as its characteristic yellow fat is visible through the glass. If a wide-mouth jar is used, it is easy to slip the room temperature foie gras out of the jar.Some of the yellow fat can be served with the foie gras — i.e. on toasted baguette.
Prepare the foie gras for low heat cooking. Sprinkle with salt and pepper. Wrap tightly with plastic wrap and refrigerate for 24 hours.
Sterilize 2 wide-mouth, 1/2-pint jars. Allow jars to cool.
Add cognac to one of the jars and swirl around to coat the interior surface. Pour the excess into the other jar and do the same. Discard the remaining cognac.
Cut the foie gras into sections sized to fit the jars snugly. Each jar will hold about 200 grams of foie gras. Stuff the pieces in the jars. Leave sufficient air space at the top for expansion. Clean the rims of the jars and seal.
Place the jars in a large pot with sufficient water to completely cover the jars. Heat the water to 175ºF and process for 45 minutes. Some fat and juices will separate from the foie gras during processing.
Allow jars to cool completely.
Store the processed foie gras in a cool dark place for at least a month before use. Let jar come to room temperature before serving. Serve with toasted French or sandwich bread.