Step 1: Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans or one 9×13 inch rectangular pan.
Step 2: In a large bowl, whisk together the flour, baking soda, salt, cinnamon, nutmeg, and ginger until well combined. Set aside.
Step 3: In a separate large bowl, combine the granulated sugar, brown sugar, vegetable oil, eggs, and vanilla extract. Whisk until smooth and well incorporated.
Step 4: Gradually add the dry ingredients to the wet ingredients, mixing on low speed or by hand until just combined. Do not overmix.
Step 5: Fold in the grated carrots and optional chopped nuts until evenly distributed.
Step 6: Divide the batter evenly between the prepared cake pans. Bake for 30-35 minutes for round pans, or 35-40 minutes for a rectangular pan, or until a wooden skewer inserted into the center comes out with moist crumbs.
Step 7: Let the cakes cool in the pans on a wire rack for 10-15 minutes, then invert them onto the rack to cool completely before frosting.
Step 8: Prepare the Cream Cheese Frosting: In a large bowl, beat the softened cream cheese and butter with an electric mixer until light and fluffy.
Step 9: Gradually add the sifted powdered sugar, one cup at a time, mixing until smooth. Beat in the vanilla extract and a pinch of salt until the frosting is creamy and spreadable.
Step 10: Once the cake layers are completely cool, frost the cake generously with the cream cheese frosting. Decorate with additional chopped nuts if desired.