01 - Preheat the oven to 350°F. Lightly grease a 9x13-inch baking dish with nonstick spray or butter.
02 - Open the cinnamon roll cans and set the icing aside. Cut each cinnamon roll into quarters using a sharp knife.
03 - Arrange the cut cinnamon roll pieces evenly in the prepared baking dish.
04 - In a large mixing bowl, thoroughly whisk together the eggs, whole milk, heavy cream, granulated sugar, vanilla extract, ground cinnamon, ground nutmeg, and a pinch of salt until fully blended.
05 - Pour the custard mixture evenly over the cinnamon roll pieces in the baking dish. Gently press the pieces into the mixture to ensure complete coverage.
06 - Drizzle the melted unsalted butter evenly over the entire casserole.
07 - Transfer the dish to the oven and bake for 35 to 40 minutes until the center is set and the top is golden brown. If browning too quickly, cover loosely with foil during the final 10 minutes.
08 - Remove from the oven and allow to cool for 10 minutes. Slightly warm the reserved icing, then drizzle evenly over the top before serving.