In a large pie pan, whisk together the milk, puree, cinnamon, nutmeg and salt.
Place the bread in the mixture, and let soak for 5 minutes. Flip, and let soak for an additional 5 minutes.
Preheat a griddle pan over medium-high heat. Add butter, and brush all over the pan.
Place the bread in the pan, and cook for 5 minutes. Flip, and cook for an additional 3 minutes.