Step 2) Combine cherries, walnuts, 3 tablespoons maple syrup, oil and pumpkin pie spice in a mixing bowl. Stir to evenly coat; set aside.
Step 3) Place each apple individually onto a 12 x 10-inch sheet of foil. Divide cherry nut filling evenly between apples, stuffing into the core of each apple. Fold foil around apples and seal tightly.
Step 4) Grill apple packets for 35 to 45 minutes or until apples are tender when pierced with a knife. Remove from grill; let rest 3 minutes.
Step 5) Stir together sour cream and 2 tablespoons maple syrup.
Step 6) Transfer each apple to a serving plate; top with a dollop of maple sour cream.