Preheat the oven to 400 degrees F.
Fold parchment sheet in half to form an 8-inch by 12-inch rectangle. With scissors, cut each folded sheet into a heart shape. Brush the inside of each sheet with 11/2 teaspoons of olive oil. Season each chicken breast with 1/2 teaspoon of Essence, 1/4 teaspoon salt, and 1/8 teaspoon of white pepper. Place one chicken breast in the center of each sheet, and top with 1/2 cup each of leeks, carrots, and celery. Lightly season the vegetables with 1/2 teaspoon of the salt. Pour 1 tablespoon of wine over each chicken breast. Fold the parchment paper over the chicken and vegetables, and seal by making small folds in the paper, turning the pouch slightly after each fold. Continue on all sides until the pouch is well sealed.
Place the pouches on a baking sheet and bake until expanded like a balloon, about 25 to 30 minutes.
To make the Carrot Jus, in a small saucepan combine the carrot juice, cayenne, allspice, ginger and remaining 1/4 teaspoon of salt. Place the pan over medium heat, and bring to a gentle boil. With a whisk, swirl the butter into the juice several pieces at a time. If the jus separates, return it to a boil while whisking for a few seconds.
Remove the papillote packages from the oven and place on serving plates. To serve, cut an "x" into each package and peel back the paper. Pour the Carrot Jus over the chicken, garnish with the parsley, and serve with steamed rice.
Yield: 4 servings