Heat the oven to 400°F. Cut 4 thin slices from the lemon. Juice the remaining portion of the lemon and set aside. Tuck 2 lemon slices under the skin of each chicken breast. Season the breasts with salt and pepper. In a 12-inch frying pan over medium-high heat, warm 1 tablespoon oil until hot but not smoking. Add the chicken breasts, skin-side down, and cook until the skin starts to brown, about 5 minutes on each side.
While the chicken cooks, prepare the sweet potatoes.

• Chop the rosemary.
• Cut the sweet potatoes into ½-inch thick wedges, toss with oil. Season with salt and pepper. Spread in an even layer on one side of a sheet pan.Transfer the seared chicken breasts to the sheet pan opposite the potatoes. Sprinkle the chicken with the rosemary.

Bake until the chicken is cooked through and the potatoes are browned and tender, about 25 minutes.
Meanwhile, prepare the nectarine salad.

• Cut the radish into thin half-moon slices.
• Chop the mint leaves.
• Cut the nectarine into ½-inch thick half-moon slices.

Warm the same pan used to sear the chicken (no need to clean it first) over medium-high heat. Add the nectarines, season with salt and drizzle with the maple syrup. Cook, turning once, until the fruit begins to soften about 5 minutes. Transfer to a medium salad bowl. Add the radishes and mint to the bowl with the nectarines and season with 2 teaspoons of lemon juice. Toss to coat the salad evenly.

Transfer the chicken breasts to serving plates. Serve with the roasted sweet potatoes and the nectarine salad.