Prep the pan: Grease a 9x13-inch baking dish. If using cinnamon rolls, open the tubes and cut each roll into 4–6 pieces. If using bread, toss cubes with cinnamon sugar.
Arrange the base: Spread cut cinnamon roll pieces or sugared bread cubes evenly in the dish.
Sprinkle any extra cinnamon sugar or small dough bits over the top.
Whisk the custard: In a large bowl, whisk eggs, milk, cream, sugar, vanilla, cinnamon, nutmeg, and salt until smooth.
Pour and press: Pour custard over the pan. Gently press the top so everything gets a little soaked. Drizzle melted butter over the surface.
Make-ahead option: Cover and refrigerate overnight (8–12 hours).
This deepens the flavor and helps the custard soak in. If baking right away, let it sit 15 minutes.
Bake: Preheat oven to 350°F (175°C). Bake uncovered for 35–45 minutes, until the top is golden, the edges are set, and the center is puffed but still soft.
If it browns too fast, tent with foil.
Glaze: If using icing packets, warm them slightly and drizzle over the hot casserole. For the cream cheese glaze, beat cream cheese and butter until smooth, then mix in powdered sugar, milk, vanilla, and salt until pourable. Drizzle generously.
Rest and serve: Let it rest 10 minutes to set.
Serve warm with extra maple syrup, berries, or a dusting of powdered sugar.