Once you beat the game, you will be able to play the game over as Skye.
To play as the boss, beat Skyes story mode. Now you can play as the boss in challenge mode!
This cheat allows you to use a spice even if you don't have it.
To do this you need at least one type of spice. On the spice selection screen use the D-Pad and highlight the spice you need that you're out of. Then using the stylus/touch screen highlight a spice you do have, then press A.
If done correctly the spice you want to use that your out of will go from 0 to -1 and appear in the box of spices being used on the top screen.
When playing as the Hero:
When you give the female character a food item to cook, make sure the item you want to dupe is in the last slot. Give her the item and with the stylus continue to press the item immediatley next to it repeatdly. It will give the item as long as you tap it.
If you open her inventory after the trick is done (by pressing X) it will undo the trick.