01 - Preheat your oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish with butter or a nonstick cooking spray.
02 - Unseal the refrigerated cinnamon rolls. Cut each roll into quarters and distribute them evenly in the prepared baking dish.
03 - In a mixing bowl, vigorously whisk together the eggs, whole milk, heavy cream, vanilla extract, ground cinnamon, and granulated sugar until thoroughly combined and smooth.
04 - Evenly pour the prepared egg mixture over the cinnamon roll pieces. Gently press down to ensure all pieces are fully moistened by the custard.
05 - Drizzle the melted unsalted butter over the entire casserole. If using, sprinkle the chopped nuts over the top.
06 - Bake uncovered for 35 to 40 minutes, or until the surface is golden brown and the center has set. If the top begins to brown too quickly, loosely cover the dish with aluminum foil for the final 10 minutes of baking.
07 - Remove the bake from the oven and allow it to cool for approximately 10 minutes before proceeding.
08 - Warm the reserved icing packets from the cinnamon rolls for about 10 seconds in the microwave until slightly softened. Drizzle the warmed icing generously over the bake before serving.