Preheat oven to 350° F. Butter and lightly flour two 8-inch round cake pans. Line with parchment paper and set aside.
In the bowl of a stand mixer fitted with a paddle attachment, combine sugar, brown sugar, and vegetable oil. Add eggs one at a time, followed by vanilla. Mix until combined.
In a large bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, allspice, and nutmeg.
Add flour mixture in three additions, mixing on low speed until just combined. Next, add all the shredded carrots, 1 cup of pistachios and 1 cup of macadamia nuts. Fold until evenly distributed.
Divide cake batter evenly between two prepared cake pans. Bake for 40-45 minutes until toothpick inserted in center of cake comes out clean. Rotate pans midway thru baking. Let cakes cool in pan for 5 minutes before unmolding. Turn cakes out on a wire rack and let cool to room temperature.