Step 1: Preheat your oven to 350°F (175°C). Grease and flour a 9-inch round cake pan (or an 8x8 inch square pan or loaf pan).
Step 2: In a large bowl, whisk together the dry ingredients: flour, granulated sugar, brown sugar, baking soda, cinnamon, nutmeg, ginger, and salt.
Step 3: In a separate medium bowl, whisk together the wet ingredients: eggs, vegetable oil, and vanilla extract.
Step 4: Pour the wet ingredients into the dry ingredients. Mix gently with a spatula until just combined. Be careful not to overmix. Fold in the grated carrots and, if using, the chopped nuts or raisins.
Step 5: Pour the batter evenly into your prepared baking pan.
Step 6: Bake for 35-40 minutes (for round/square cake) or 45-55 minutes (for loaf cake), or until a wooden skewer inserted into the center comes out clean.
Step 7: Let the cake cool in the pan for 10-15 minutes, then invert it onto a wire rack to cool completely before frosting.
Step 8: To make the Cream Cheese Frosting: In a medium bowl, beat the softened cream cheese and butter with an electric mixer until smooth and creamy. Beat in the vanilla extract. Gradually add the sifted powdered sugar, one cup at a time, beating until smooth and fluffy. If too thick, add a tiny bit of milk; if too thin, add more powdered sugar.
Step 9: Once the cake is completely cool, spread the cream cheese frosting evenly over the top and sides. Garnish with additional chopped nuts, cinnamon, or orange zest, if desired. Slice and serve! Enjoy!