Cut panettone into ½ inch slices, and cut each slice in half. Remove any hard crust. Arrange in rows in the baking dish, overlapping to fit.
Mix together eggs, milk, cream, sugar, vanilla, and cinnamon.
Pour egg mixture on top of bread, coating all pieces. Press the bread into the egg mixture if needed. Cover and refrigerate overnight.
To Bake
Turn oven to 350˚F. Remove baking dish from the refrigerator to the countertop while the oven preheats.
If adding streusel topping, mix all ingredients together**, using a pastry cutter or two forks, and sprinkle over the top of the dish.
Bake uncovered for 45-60 minutes, or until a knife comes out clean. If the top browns too quickly, tent loosely with foil for the remainder of cook time.
Remove from the oven and allow to rest for 5-10 minutes before serving. The dish will puff up while baking, and settle after it's been out of the oven for a few minutes.
Notes
Nutrition calculated with regular bread.
*Prep streusel topping the night before if desired. Save any leftover topping and use to sprinkle on muffins, quick breads, or pancakes.
Allow Panettone slices to dry out before using so that it absorbs all of the batter.
Add an extra egg yolk to the batter for a thick, more custard-like result.
Refrigerate leftovers in a covered container for up to 4 days. Unbaked, or baked and cooled Panettone French toast can be frozen for up to 6 weeks. Wrap first in plastic, then in foil for best freezer protection.
Thaw frozen casserole in the refrigerator before baking, or reheating. Reheat portions on the stovetop or pop them in the toaster.