Place chicken on cutting board, pat dry and reserve neck for stock. Remove the skin in one piece by slicing down the backbone and then peeling forward. Once skin is loosened all the way down to the end of the legs and wings, pull or trim off to remove. Remove breast, tenders, as well as all the leg meat. Cut bones into larger pieces and use for stock.
Cut the chicken leg meat, fat and livers into small pieces, removing as many tendons and sinew as possible. Place in freezer until par-frozen on the exterior.
Transfer to a food processor and puree until homogenous. Add the eggs, nutmeg, salt, and pepper and continue to process until very smooth. Be sure to keep chilled to prevent separating.
Place a tamis over a medium bowl set on top of a bowl of ice water. Pass mousse through the tamis for an extra smooth mousse.
Clean and dry the food processor and return the mousse to the bowl. Process on low while streaming in the cream to make an airy texture.
Add the tomato paste, scrape down the sides with a spatula and process again to combine well.
Line a countertop with a layer of plastic wrap about 2 feet long and 1.5 feet wide.
Transfer mousse in a loose log-shape into the middle, about 4 inches away from where you are standing.
Slowly roll and mold the mousse away from you into a tight log, poke the plastic a few times if you see air bubbles to release them. Roll tightly and tie off the ends. Freeze overnight.
Set a circulator in a water bath to 62°C.
Place a large sheet of parchment paper on a work surface. Butterfly the chicken breasts to reach an even thickness. Place on parchment into a rectangular shape. Place another parchment on top and pound out the breasts into about 1/4-inch layer, arranging as necessary to maintain a rectangular shape.
Lay out the chicken skin in a similar rectangular shape and sprinkle with tarragon leaves, salt and pepper. Flip the pounded out breast on top of the skin, and season with salt and pepper. Remove the plastic wrap from the frozen mousse and place it in the middle of the chicken. Roll the meat and skin around the mousse to completely encase. Trim any excess skin from the sides and use for chips.
Wrap the log in plastic wrap very tightly to mold the meat around the mousse and tie off the ends.
Bring a large pot of water to a boil.
Place the plastic-wrapped chicken log into a shrinkable and heat proof pouch. Leave a few inches of plastic on each end and cut and reserve a 2-inch thick ring of shrink pouch from the open end. Seal in a chamber sealer.
Place sealed chicken roulade in boiling water for approximately 10-15 seconds, to form a tight log shape. Remove, pat dry, and place thermocouple tape in-between the middle of the log and the reserved plastic ring, securing with super glue if needed. Return to the boiling water again to tighten the ring and secure the tape. Probe the log with a thermocouple so that the tip of the probe hits the center of the mousse.
Place roulade in the water bath until the interior reaches 62°C for at least 10 minutes. It will take about 3 hours.
Preheat oven to 300°F. Scrape as much fat as possible from the excess chicken skin. Lay flat onto a Silpat-lined baking sheet in a single layer. Sprinkle with salt, and then top with another Silpat and baking sheet to keep it flat. Bake for 2 hours, or until golden brown and crispy.
Transfer tray of tomato roses to the oven at 300°F for 1 hour to dry the exterior and reach a jammy texture in the center.
Remove chicken from bath and allow to cool to 55°C in core.
Once the chicken has decreased in temperature, pass the sauce through a sieve and keep warm. Return polenta and brussels sprouts to the water bath to reheat.
Remove chicken from the pouch and plastic wrap and dry the skin well. Heat a large sauté pan over medium - high heat and add a splash of oil, butter and tarragon. Sear the chicken on all sides, turning and basting often. Continue searing for about 5 minutes, or until golden brown on all sides.
Slice the chicken into 4 portions. Place a spoonful of polenta onto a serving plate and top with chicken. Place brussels sprouts and tomatoes around the chicken, spoon on the sauce and garnish with chicken skin chips and brussels sprouts leaves.
