She loves bread. That's really all you need to know. Not much else is really known about her, in fact! Is she MADE of bread? Is she inside of a gigantic robotic-like suit comprised of baked goods?
We do know she is a mouse of some kind and, being a mouse, she also loves cheese. So, naturally, Grilled Cheese would drive this mouse WILD. Cheese AND bread? TOGETHER?!
Collect Packets of Flour in the Windmill to create Grilled Cheese and free the Windmill from her breaded tyranny!
Mousehunt Wiki page