For glaze: In a small saucepan heat apple jelly, soy sauce, thyme, lemon peel, and ginger just until jelly is melted. Set aside 1/4 cup of the glaze.
Preheat broiler. Place chicken on the unheated rack of a broiler pan. Broil 4 to 5 inches from the heat for 12 to 15 minutes or until chicken is no longer pink (170 degrees), turning once and brushing with the remaining glaze the last 5 minutes of broiling.
Meanwhile, lightly coat a large saucepan or Dutch oven with cooking spray. Heat saucepan over medium heat. Add apples, leek, and garlic; cook for 3 minutes. Add the reserved 1/4 cup glaze and apple cider; bring to boiling. Add spinach and toss just until wilted. Season to taste with salt and black pepper.
To serve, cut each chicken piece crosswise into 6 to 8 slices. Divide the spinach mixture among dinner plates. Top with sliced chicken.