Cut the bread loaf into 1-inch cubes. Place on a large baking sheet. Toast in the oven for 5-10 minutes at 350. Cool before transferring to a prepared baking dish.
Combine the eggs, whole milk, heavy cream, sugar, vanilla, and cinnamon in a large bowl. Whisk until eggs are fully combined.
Grease a 9x13 baking dish. Place toasted bread cubes in the baking dish and pour egg mixture evenly over the bread. Cover with plastic wrap and chill in the refrigerator overnight.
Preheat oven to 350; bake for 45-60 minutes.
Remove from oven and cool for 5 minutes before serving.
Top with powdered sugar and syrup.