1. Preheat oven to 350º F. Butter and flour 2 - 8-inch cake pans. Set aside.
2. In the bowl of a stand mixer beat the eggs and brown sugar on medium-high speed until mixture is light and thick, about 3-4 minutes.
3. In a small bowl, whisk together the oil, buttermilk and vanilla.
4. On low speed, gradually over about 1 minute, add in the oil mixture into the egg-sugar mixture. (if you do this too fast you lose the volume from beating the eggs and sugar.)
5. In a small bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and ginger.
6. Fold the flour mixture into the egg mixture with a spatula When most of the flour mixture has been incorporated, add the carrots, raisins and nuts, and fold until the batter is homogenous. Pour the batter evenly between the prepared pans. Bake for 38 - 42 minutes or until a toothpick comes out clean. Cool completely in the pan on a wire rack.
Make the Cream Cheese Icing
1. In the bowl of a stand mixer, beat the cream cheese on medium speed until smooth, about 3 minutes. Add in the butter and continue to mix for another minute.
2. Add in the confectioner's sugar and vanilla. Beat for 2-3 minutes, or until well very smooth.
Assemble the Cake
1. Remove the cakes from the pans. Split each in cake in half creating two layers. You now have 4 layers of cake.
2. Place layer one and place cut-side up, on a cake plate. Spoon about 1/4 of the frosting onto the layer and spread it evenly to the edges. Repeat with remaining 3 layers.
3. Place the top layer, cut-side down, on top and press down to adhere. Spread the remaining icing over the top and to the edge. Decorate as desired.