Peel and seed squash, then cut into 1/2 inch pieces. Mince garlic.
Using meat pounder, pound thick part of chicken breast to 3/4 to 1 inch thickness. Season chicken with salt and pepper.
Place chicken, skin side down, in cold 12 inch skillet, Cover and place over medium heat. Cook, without moving , unitl skin is golden brown, about 15 minutes. Continue to cook, covered, until skin is deep golden brown, rotating skillet halfway through cooking. Transfer to platter, tent with foil.
While chicken cooks, melt butter in large sauce pan over medium heat. Add garlic and cook until fragrant, about thirty seconds. Stir in orzo and cook for one minute. Add squash and broth, bring to boil, and cook, stirring often, until orzo and squash are both tender, about 15 minutes.
While orzo is cooking grate parmesan (1 cup) mince three tablespoons chives and squeeze 1 teaspoon lemon juice.
Off heat stir in babay spinach, nutmeg, parmesan, 2 tablespponsschives and lemon juice. Let sit unccovered for 5 minutes to thicken. Sprinkle renaining chives over chicken.