Preheat your oven to 375°F (190°C). Use the 2 tablespoons of melted butter to grease a 9x13 inch baking dish, ensuring the sides are well coated to prevent sticking.

Remove the cinnamon rolls from the cans and set the included icing packets aside. On a clean cutting board, cut each cinnamon roll into quarters (four pieces per roll). Place the cut pieces directly into the prepared 9x13 inch baking dish.

Prepare the Custard Mixture: In a large mixing bowl, whisk together the 4 large eggs until they are lightly beaten and frothy.

Add Wet and Dry Ingredients: Pour the heavy cream or whole milk into the egg mixture. Add the granulated sugar, light brown sugar, vanilla extract, ground cinnamon, and ground nutmeg. Whisk this mixture thoroughly until the sugars are completely dissolved and the ingredients are well combined into a smooth custard.

Combine and Soak: Pour the prepared custard mixture evenly over the cut cinnamon roll pieces in the baking dish. Gently toss or stir the rolls to ensure all pieces are coated and submerged in the custard. Allow the casserole to sit for 5 to 10 minutes to allow the bread pieces to absorb the liquid fully.

Bake the Casserole: Place the baking dish into the preheated 375°F (190°C) oven. Bake for 30 to 35 minutes, or until the casserole is golden brown on top, puffed up, and the center is set (a toothpick inserted near the center should come out clean).

Prepare the Glaze: While the casserole is baking, prepare the boosted glaze. Open the reserved icing packets and scrape the contents into a small mixing bowl. Add the powdered sugar and 1 tablespoon of milk or cream. Whisk until smooth and drizzle consistency is reached. If the glaze is too thick, add the second tablespoon of milk, a few drops at a time.

Glaze and Serve: Remove the casserole from the oven and allow it to cool for 5 minutes. Drizzle the prepared glaze generously over the warm casserole. Serve immediately while the casserole is still warm.