If using bacon, preheat oven to 375 and arrange bacon on slotted broiler pan or a wire rack set inside a rimmed baking sheet. Bake bacon until very crisp and brown, 15-18 minutes. Remove bacon and switch on broiler.
In a large shallow dish, whisk up eggs, milk, allspice, nutmeg and a fat pinch of salt.
In a small pot over medium heat, combine maple syrup and cranberry sauce, and warm.
Arrange 4 slices of French toast on a baking sheet and top with 3 slices of bacon, if using, and some sliced turkey. Top with cheese and broil to melt. Transfer sandwiches to plates and top with remaining French toast. Serve cran-maple sauce over the top of the sandwiches or alongside.