1. Preheat oven to 350 degrees F. Line 24 standard muffin pan cups with paper baking cups; coat paper cups with nonstick cooking spray.
2. Combine cake mix, eggs, buttermilk, oil, cinnamon, nutmeg, and allspice in large bowl; beat according to package directions. Fold in the zucchini and pineapple; mix well to distribute evenly. Divide the batter evenly between the muffin cups.
3. Bake 20 to 22 minutes or until toothpick inserted into centers comes out clean. Cool 20 minutes in pan on wire rack. Transfer to wire rack to cool completely.
4. Combine powdered sugar, sour cream, and butter in large bowl with electric mixer at low speed. Beat at medium speed until smooth. Stir in 2 teaspoons orange peel. Frost cooled cupcakes with an offset spatula. Garnish with additional orange peel, if desired. Serve at room temperature. Store leftover cupcakes in refrigerator.