Measure 1/4 cup of the Ginger-Apple Glaze. Place chicken on the grill rack directly over medium heat; grill for 12 to 15 minutes or until no longer pink (170 degrees F), turning once halfway through grilling and brushing often with the 1/4 cup Ginger-Apple Glaze during the last 5 minutes of grilling.
Meanwhile, lightly coat an unheated large saucepan or Dutch oven with nonstick cooking spray. Preheat over medium heat. Add apple, leek, and garlic; cook for 3 minutes. Add 1/4 cup of the Apple Glaze and the apple juice; bring to boiling. Add spinach; toss just until wilted. Season to taste with salt and pepper.
To serve, slice each chicken breast crosswise into 6 to 8 pieces. On 4 dinner plates, arrange spinach mixture; top with sliced chicken.
In a small saucepan, combine apple jelly; soy sauce, thyme; lemon peel; and ginger. Heat and stir just until jelly is melted. Makes 2/3 cup.