Preheat oven to 350 degrees F. Grease two 8-inch cake pans and line bottoms with parchment paper.

In medium bowl, combine flour, baking powder, baking soda, salt and spices.

In large mixing bowl, whisk together oil, sugars, vanilla extract and eggs. Add dry ingredients and mix to combine, taking care not to overmix. Fold in carrots and walnuts.

Portion batter equally between pans and spread evenly. Bake 45-60 minutes, until toothpick inserted in center of each cake comes out clean. Chill completely in refrigerator before unmolding.

In large bowl, beat cream cheese and butter until smooth. Add powdered sugar, 1 cup at a time, beating thoroughly between additions, then stir in vanilla.

Unmold both cakes and lay on parchment paper on flat surface to slice each cake in half. Using ruler, measure halfway up side of each cake and insert toothpick to mark spot. Continue measuring around sides so there are at least four toothpicks inserted. Take string and snuggly wrap around cake on top of each toothpick. Cross ends of string in front of cake and pull them away from each other to slice cake into two even layers.

Choose one of the four layers to be bottom layer and evenly smooth on about ⅔ cup frosting. Top with another layer of cake and repeat until there are four cake layers and three frosting layers. Make sure cake edges line up. Smooth remaining frosting over top and sides. Refrigerate until set, then slice and serve.

Garnish idea: Use vegetable Y peeler to shave extra carrots into ribbons to make curls. Roll up each carrot ribbon starting at narrow end and rolling toward wider end. Arrange as desired onto cake, pressing lightly into frosting to hold curl.