01 - Preheat oven to 175°C (350°F). Grease a 23x33 centimeter (9x13-inch) baking dish.
02 - Open the cinnamon roll cans, reserving the icing for later. Cut each cinnamon roll into quarters and evenly scatter the pieces across the prepared baking dish.
03 - In a large bowl, vigorously whisk together the eggs, whole milk, heavy cream, vanilla extract, ground cinnamon, and granulated sugar until uniformly smooth.
04 - Pour the prepared egg mixture evenly over the cinnamon roll pieces in the baking dish. Gently press down to ensure all pieces are coated.
05 - In a small bowl, combine the melted butter, brown sugar, and ground cinnamon for the topping. Drizzle this mixture evenly over the entire surface of the casserole.
06 - Bake for 35 to 40 minutes, or until the casserole is golden brown and set in the center.
07 - Allow the casserole to cool slightly. Drizzle the reserved icing over the top. Serve warm.