Preheat the grill to medium heat and brush some oil onto the grates.
Bring a medium saucepan of water to a boil. Add the spelt and return to a boil. Lower the heat to a simmer, cover, and cook until the berries are tender but not mushy, 15 to 20 minutes. Drain and set aside.
Sprinkle the chicken all over with 1/2 teaspoon salt and some pepper. Grill until nicely marked and the chicken reaches an internal temperature of 165 degrees F, 18 to 20 minutes. Set aside to rest.
Put the lemon juice in medium bowl. Thinly slice the pears and the fennel lengthwise with a mandoline into the bowl. Toss with the lemon juice. Add the spelt, watercress and oil . Toss to dress evenly. Season with 1/8 teaspoon salt and some pepper.
Divide the salad and chicken evenly among four plates. Using a vegetable peeler, shave the Gruyere or Gouda cheese over each plate. Serve.