Step 1Clarify the stock or broth: Break the eggs into a small bowl, saving the shells. Remove the egg yolks; they can be kept covered in the refrigerator for another use. Pour the stock into a medium saucepan, and add the egg whites and reserved shells, whisking the contents thoroughly. Place the saucepan over medium heat and bring to a simmer, stirring gently but constantly. Reduce the heat so the stock barely simmers; stop stirring and cook an additional 15 minutes. The eggs will coagulate to form a "raft," drawing impurities from the stock. Remove the pan from the heat and gently push the raft down to ladle out the stock; be careful not to disturb the raft and cloud the stock. Discard the raft. Measure the amount of stock; you will need 1 3/4 cups. If you have more than 1 3/4 cups, return it to a clean saucepan, simmer and reduce. Set aside.
Step 2Rinse the chicken livers under cold water, and pat dry on paper towels. Heat 2 tablespoons of the butter in a large skillet over medium-high heat until melted and sizzling. Add the chicken livers and saute until browned on all sides, about 5 minutes. Add the onion, stirring until the onions are tender and browned, 4 to 5 minutes. Reduce the heat if the onions start to brown too quickly. Remove the pan from the heat.
Step 3Place the chicken livers and onions in a food processor. Add one-fourth cup of the chicken stock to the skillet, moistening the bottom of the pan. Scrape the bottom of the pan and pour the stock and drippings into the food processor. Add the Worcestershire sauce, paprika, nutmeg, salt, pepper and Cognac. Puree until smooth.
Step 4With the processor running, add the remaining butter piece by piece through the feed tube, and continue to process until all the butter has been incorporated. This makes slightly more than 2 cups of pate.
Step 5Pour the liver pate into a 3-cup oval casserole. Chill it in the refrigerator, uncovered, until it sets up and is firm, about 1 hour. Once the pate is set, cover the casserole with plastic wrap, pulling it tight over the top of the dish so it does not touch the pate and refrigerate overnight.
Step 6Place one-fourth cup of the chicken stock in a small bowl. Drizzle the powdered gelatin over the stock to moisten and soften the gelatin. Pour 1 1/4 cup of chicken stock into a small saucepan, and bring to a gentle simmer over medium heat. Pour the softened gelatin into the pan, stirring or whisking constantly until the gelatin is completely dissolved. Remove the pan from the heat.
Step 7Pour the gelatin-infused stock into a small metal bowl, and stir in the Monbazillac and lemon juice. Put the bowl over another bowl filled with ice water to cool the mixture. Stir gently until the gelatin just begins to thicken but is not yet set. Immediately remove the bowl from the ice water bath.
Step 8Remove the pate from the refrigerator and decorate the top of it with the chives. Gently spoon about one-half cup of the gelatin mixture over the top in an even layer. Place the pate back in the refrigerator and chill until the gelee is set, about 45 minutes.
Step 9Pour the remaining gelee into a shallow glass dish and chill until it is set.
Step 10When you are ready to serve the pate, place the pate dish on a platter. Coarsely cut or chop the gelee from the shallow glass dish into half-inch cubes and spread them around the pate on the platter. Serve with crisp toasted French bread.