Cinnamon Roll Casserole

Preheat oven to 325° and grease a glass baking dish. Cut cinnamon rolls into thirds and layer in dish. In a large bowl, whisk together eggs, milk, vanilla, and cinnamon. Pour mixture over cinnamon rolls and bake until egg is cooked through and cinnamon rolls are deeply golden, 20 to 22 minutes. Let cool about 10 minutes, then drizzle with cinnamon roll icing and pour over maple syrup (if using).