1. Preheat oven to 350 degrees Fahrenheit.
2. Grease one loaf pan.
3. In the bowl of a stand mixer, cream sugars and butter together until light and fluffy.
4. Add in the eggs and mix again.
5. In a separate bowl, whisk together flour and baking soda.
6. Add the flour mixture to the sugar mixture and mix just until incorporated.
7. Add in mashed bananas and mix.
8. Next add the carrots and mix again.
9. Finish up with the remaining spices (cinnamon, nutmeg, ginger) and vanilla and walnuts.
10. Mix again.
11. Pour the mixture in the greased loaf pan and spread evenly.
12. Bake in the oven for approximately 45-48 minutes, but check often to make sure the cake is not over done.
13. You want the center to be slightly underdone when you remove it from the oven.
14. Remove it from oven and allow to cool completely in loaf pan.  This will ensure it finishes baking in the middle without drying out the edges.
15. Once cooled, flip the loaf out onto cooling rack.

Directions for Icing

1. While cake is baking, using a stand mixer, mix butter and cream cheese together.
2. Add in powder sugar and mix again.
3. Add the vanilla and mix one more time.
4. Spread on completely cooled cake. 
5. Top the icing with additional toasted walnuts if desired.