Begin by cutting 12-16 store-bought unfrosted cinnamon rolls into 1-inch pieces. Arrange them evenly in a greased 9x13 inch baking dish, ensuring each piece is well-distributed.

In a large mixing bowl, whisk together 6 large eggs, 2 cups of whole milk, 1 cup of heavy cream, ½ cup of granulated sugar, 2 teaspoons of ground cinnamon, 2 teaspoons of vanilla extract, ¼ teaspoon of freshly grated nutmeg, and a pinch of salt until smooth.

Pour the prepared custard mixture evenly over the cinnamon roll pieces in the baking dish, pressing gently to ensure all pieces are coated. Cover and refrigerate for at least 4 hours or overnight.

Preheat your oven to 350°F (175°C). Remove cover and bake uncovered for 35-45 minutes until golden-brown and puffy.

Whisk together 1 cup of powdered sugar, 2 tablespoons of milk or heavy cream, and 1 teaspoon of vanilla extract until smooth, adjusting consistency as needed.

Once the casserole is baked, allow it to cool slightly for 10 minutes. Drizzle the glaze generously over the warm casserole.