Preheat your oven to 350 degrees Fahrenheit. Grease 3 6-inch round cake pans and line the bottoms with parchment paper.
In a medium bowl, whisk together the flour, cinnamon, nutmeg, ginger, allspice, baking powder, baking soda, and salt. Set aside.
In a large bowl, cream together the butter, granulated sugar, and light brown sugar until fluffy.
Add the eggs and vanilla, mixing until smooth and slightly fluffy.
Alternate adding the dry ingredients and the buttermilk to the butter mixture, mixing until combined.
Fold in the shredded carrots until evenly dispersed.
Divide the batter between the prepared cake pans and bake for 36-41 minutes, or until a toothpick comes out clean. Let cool completely.