Preheat oven to 350 degrees F. Grease and flour a 13×9-inch baking pan.
In a mixing bowl, beat together the sugar, oil, and vanilla just until combined. At medium speed, beat in the eggs one at a time.
Stir in the flour, nutmeg, cinnamon, baking powder, and baking soda. Add the carrots, pineapple, and nuts. Stir just until combined.
Pour the batter into the prepared pan. Bake until a knife inserted into the center comes out clean, about 45 minutes.
Remove from the oven, place onto a rack, and let cool.
Combine cream cheese, butter, orange zest, and confectioners’ sugar and beat until smooth. Adjust the amount of confectioners’ sugar depending on how stiff you like the icing to be. Frost the cake and top with shredded coconut (if you like).