1Heat oven to 350°F. Place Reynolds Baking Cup in each of 16 regular-size muffin cups. In large bowl, beat cake mix, cinnamon, nutmeg, water, 1/2 cup butter, the vanilla and eggs with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. Stir in chopped apple. Divide batter evenly among muffin cups.
2Bake 18 to 23 minutes or until toothpick inserted in center comes out clean. Cool 5 minutes; remove from pan to cooling rack. Cool completely, about 30 minutes.
3In large bowl, beat 1/2 cup unsalted butter, cream cheese and maple syrup with electric mixer on medium speed until fluffy. Add powdered sugar; beat until smooth. Pipe frosting onto cooled cupcakes. Sprinkle with glazed walnuts. Store loosely covered in refrigerator.