01 - Preheat oven to 350°F. Grease and line two 8-inch round cake pans with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, cinnamon, nutmeg, ginger, and salt until well blended.
03 - In a large bowl, whisk granulated sugar, brown sugar, vegetable oil, eggs, and vanilla extract until smooth and fully incorporated.
04 - Gradually add dry ingredients to wet ingredients, mixing with a spatula just until combined. Do not overmix.
05 - Fold in grated carrots and chopped walnuts until evenly distributed throughout the batter.
06 - Divide batter evenly between prepared pans. Smooth the tops with a spatula. Bake for 35-40 minutes, or until a toothpick inserted in the center comes out clean.
07 - Let cakes cool in pans for 10 minutes, then carefully turn out onto a wire rack to cool completely before frosting.
08 - Beat cream cheese and butter together until creamy and smooth. Add powdered sugar, vanilla, and salt; beat until light and fluffy.
09 - Once cakes are completely cool, spread a layer of frosting on one cake layer. Top with second layer and frost the top and sides evenly. Decorate with extra walnuts if desired.