Prep the pan: Heat oven to 350°F (175°C). Grease an 8x8 or 9-inch baking dish.
Cut the rolls: Slice cinnamon rolls into 1–2-inch pieces. If they’re very fresh, let them sit out for 15 minutes to dry slightly for better texture.
Make the custard: In a bowl, whisk eggs, milk, sugar, vanilla, cinnamon, nutmeg, and salt until smooth.
Combine: Add the roll pieces to the dish.
Pour the custard evenly over the top. Gently press the rolls down so they soak it up.
Rest (optional but helpful): Let sit for 10–20 minutes to absorb more custard. This yields a creamier center.
Butter and bake: Drizzle melted butter over the top.
Bake 35–45 minutes, until set in the center and golden at the edges. A knife inserted in the middle should come out mostly clean.
Finish and serve: Let cool 5–10 minutes. Top with icing or glaze.
Serve warm, optionally with ice cream or whipped cream.