Step 1. Preheat your oven to 400 degrees. Melt the butter in a microwave-safe dish. Add in the chopped sage, garlic slices, half of the salt and pepper.
Step 2. In a large braising pan, add the brussel sprouts, apples and sweet potatoes. Pour on about ⅓ of the butter mixture and mix to coat the vegetables.
Step 3. Place the spatchcocked chicken on top of the vegetables. Rub the remaining butter mixture all over the skin of the chicken and pour some under the skin that is covering the breasts. Sprinkle the rest of the salt on the chicken and place two of the lemon wedges in the pan.
Step 4. Set your Thermopro thermometer to the chicken setting and place it in the thickest part of the chicken. Roast the chicken until the internal temperature reaches 165 degrees. Squeeze some lemon over the chicken.
Step 5. Allow the chicken to rest for 10 minutes before carving.
Step 6. Top chicken with the vegetables and pan juices, and garnish with sage leaves.
