Preheat oven to 350°F. Grease and flour 2 (9-inch) cake pans. In a large bowl, beat cake mix, cinnamon, and nutmeg on low speed. Add mayonnaise, eggs, carrots and pineapple. Beat for 30 seconds or until moist. With mixer on medium speed, mix for 2 minutes. Stir in walnuts.
Pour into pans.
Bake for 30 minutes. Cool for 10 minutes in pans. When completely cool, frost with cream cheese frosting.