Fold the rib bones inward toward the breast meat. This helps prevent the bones from puncturing the vacuum bag during sealing and cooking.
Season the chicken with salt (about 1% by weight) and garlic powder.
Place the rosemary sprigs (and optional bay leaf) between the rib cage and the bag rather than directly against the skin. This cushions the bones while preventing the herbs from imprinting the skin.
Massage the skin so it completely covers the breast before vacuum sealing.
Vacuum seal the chicken (or use the water displacement method).
Cook at 140°F (60°C) for 6 hours
Remove the chicken from the bag, reserving all of the cooking juices.
Remove the rib bones and wing bone. Trim away any excess fat if desired.
Pat the chicken completely dry with paper towels.
Season both sides with poultry seasoning or your favorite all-purpose seasoning.
Mix a little additional seasoning into the reserved cooking juices.
Heat a cast iron skillet over medium high.
Add chicken fat or oil to the pan.
Place the chicken skin-side down and press gently to maximize contact with the pan.
Cook until the skin becomes deep golden brown and crispy.
Flip briefly to brown the second side.
Because the chicken is already perfectly cooked, the sear only takes a minute or two.
Spread a generous spoonful of cauliflower purée (or your preferred side) onto each plate.
Slice the chicken into several thick slices and arrange over the purée.
Drizzle with the seasoned cooking juices.
Finish with a small spoonful of the flavorful pan fat, a squeeze of fresh lemon, and microgreens if desired.