In a bowl, stir together the thousand island salad dressing, pineapple-apricot preserves, grated onion, dry onion soup mix, and cinnamon until well blended. Place chicken in a large, oiled baking dish. Arrange potato halves around the edges of the pan, fitting chicken and potatoes tightly together in a single layer. Brush sauce over chicken, coating completely. Cover with aluminum foil.
Bake in the preheated oven for 40 minutes. Increase oven temperature to 375 degrees F (190 degrees C) and remove foil. Continue baking 15 minutes more, or until potatoes are fork-tender and chicken is no longer pink in center. Both should have a beautiful golden brown glaze.