In a large mixing bowl, combine eggs, milk, and vanilla. Whisk until well mixed.
On a small plate, mix sugar, cinnamon, and nutmeg.
Slice the challah bread into 1-inch slices. Spread a thin layer of butter on each side (about 1/2 tablespoon per side).
Dip each slice into the cinnamon sugar mixture and arrange them in a buttered 11x7 baking dish. Save some extra cinnamon sugar for later use.
Pour the egg mixture over the bread. Cover and refrigerate overnight.
When it's time to bake, preheat the oven to 350 degrees F. Remove the cover, sprinkle the remaining cinnamon sugar, and bake for 35-40 minutes or until golden brown.
Serve your delightful creation with a dollop of Crème fraîche and a drizzle of chocolate sauce. Enjoy the sweet, cinnamon-infused goodness!