Preheat oven to 350 degrees. Prepare 3-9 inch round pans. Grease and flour pans. (I usually cut out parchment paper and line bottom of cake pans, this will make cakes come out of pans very easily.)
Put all dry ingredients in large bowl, Flour, cinnamon, baking soda and salt whisk until combined, set aside.
Stir together white sugar, vegetable oil, eggs and vanilla in large bowl. Beat on medium speed of mixer 2 minutes. Until all ingredients are well combine.
Stir in the dry ingredients and mix until just combine do not over mix.
Fold in carrots and mix well until all combine.
Pour into prepared 3 - 9 inch round pans. Bake at 350 degrees for 35-45 minutes. (depending on how your oven cooks)bake until toothpick comes out clean.
Once cakes are cooled remove from pans and put on a cooling rack. In the meantime start preparing Icing.
For the Icing:
With an electric mixer, mix the butter and cream cheese together, about 3 minutes on medium speed until very smooth. Scrape down the sides and bottom of the bowl to ensure even mixing.
Add the vanilla extract and mix. Slowly add the powdered sugar. Keep adding until you get to desired sweetness and thickness. Once you have reach that consistency. Remove 1-1/2 - 2 cups icing and set aside to ice the sides of cake.
The remaining icing in bowl add the chopped walnuts, crushed pineapple and combine well. Icing will be kind of runny but that's OK! Now you are ready to start assembling your cake.
First Layer put the Icing with pineapple and nuts, be generous, then add second layer repeat step, then add 3rd-layer this time using the icing you set aside Ice the sides of cake. Finishing with the top of the 3rd layer using the icing you used in -between the layers ice top of cake and Sprinkle with unsweetened shredded coconut.