Prep the Crockpot: Spray the inside of a 6-quart crockpot with nonstick cooking spray. This ensures the casserole doesn’t stick while baking and makes cleanup much easier.
Arrange the Cinnamon Rolls: Unroll the cinnamon rolls and cut each into quarters. Spread them evenly across the bottom of the crockpot, creating a layered base that will soak up the custard.
Make the Custard: In a medium bowl, whisk together eggs, milk, brown sugar, salt, vanilla, cinnamon, and nutmeg. Mix until smooth and well combined. The custard adds sweetness and helps the rolls bake into a tender, gooey texture.
Pour Custard Over Rolls: Carefully pour the custard mixture over the cinnamon roll pieces, pressing lightly to ensure each piece is coated and starts absorbing the mixture. The custard should settle into the crevices of the cinnamon rolls.
Add Optional Mix-Ins: If desired, sprinkle chopped nuts or mini chocolate chips evenly over the top. This adds extra flavor and texture to the finished casserole.
Cover and Cook: Place the crockpot lid on top and cook on low heat for 2 to 3 hours. Check occasionally after 2 hours; the casserole is ready when the custard is set and a toothpick inserted into the center comes out mostly clean.
Prepare the Glaze: While the casserole cools slightly, whisk powdered sugar, milk, and vanilla in a small bowl until smooth. Adjust milk for desired drizzle consistency.
Drizzle and Serve: Once the casserole is slightly cooled, drizzle the glaze over the top. Serve warm, either directly from the crockpot or transferred to a serving dish.
