Grease two 9-inch pans. (If making a sheet cake instead, grease a 9x13 inch pan). Preheat the oven to 350 degrees F.
In a small bowl, combine the flours, baking soda, xanthan gum, salt, cinnamon, and nutmeg.
In a larger bowl, add the sugars, eggs, oil and vanilla extract and beat until combined.
Add the milk, pureed carrots and pineapple and stir to combine.
Add the flour mixture and toasted coconut (if using) and stir just until combined. Be careful not to over-stir.
Pour equal amounts of batter into the pans. Bake for 35-40 minutes or until a toothpick inserted into the center of the cake comes out clean. Let the cake cool in the pans for about 5 minutes and then carefully invert onto a wire rack to cool completely.
To Make the Cream Cheese Frosting: Place the butter and cream cheese in a large mixing bowl and beat with an electric beater until combined. Add the powdered sugar and vanilla extract and beat until smooth. Can be made in advance.
Frost the top side of the bottom layer and set the second layer on top of it. Frost the rest of the cake.
To Make the Marzipan Carrots: Use a ratio of 2:1 yellow to red food coloring to make orange-colored marzipan. Use green food coloring to color a little bit of marzipan green for the leaves. Shape the orange marzipan into small carrots and set them on wax paper or other non-stick surface. Break of tiny bits of green marzipan, shape them into foliage, and press them to the carrots. Set aside until ready to use. These can be made several days in advance, just keep them covered/airtight so they don't dry out.
Arrange the marzipan carrots on the cake.
Cut the cake into wedges so that each slice has at least one marzipan carrot on it. Serve and enjoy!