01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish with butter or nonstick spray.
02 - Open the cinnamon roll cans and reserve the icing. Cut each cinnamon roll into quarters and distribute the pieces evenly in the prepared baking dish.
03 - Whisk the eggs, milk, heavy cream, vanilla extract, ground cinnamon, ground nutmeg, and salt in a large bowl until combined.
04 - Pour the custard mixture evenly over the cinnamon roll pieces, ensuring all are thoroughly soaked.
05 - In a small bowl, combine melted butter and packed brown sugar. Drizzle this mixture over the casserole and sprinkle with chopped pecans or walnuts if desired.
06 - Bake uncovered for 40 to 45 minutes, or until golden brown and the center is set. If top browns too quickly, loosely cover with foil for the final 10 minutes.
07 - Remove from the oven and allow to cool for 10 minutes.
08 - In a bowl, whisk reserved icing with cream cheese and milk until smooth. Drizzle over the warm casserole.
09 - Slice and serve warm, optionally garnished with maple syrup.