The best part of this dish is the advance prep! Do all the work the night before and pop it in the oven the next morning.

Butter a 9"x 13" baking dish.
Toss bread cubes into prepared dish. Whisk eggs, egg yolks, cream, milk, sugar, vanilla, cinnamon, nutmeg, and salt in a medium bowl.
Pour over challah, pressing down to help it soak up custard. Cover and chill at least 2 hours or up to one day. Keep chilled.
Preheat oven to 375°F. Pulse pecans, butter, brown sugar, and salt in a food processor until nuts are coarsely chopped.
Scatter pecan crumble over soaked challah. Place dish on a rimmed baking sheet and cover tightly with foil. Bake until warmed through (a knife inserted into the center should feel warm to the touch), about 27 Minutes.
Remove foil and bake until deeply browned, 40 Minutes longer. Let cool slightly before serving with maple syrup or honey.
