Preheat Oven & Butter Dish: Preheat your oven to 375°F (190°C). Pour the 2 tablespoons of melted salted butter into the bottom of a 9x13-inch ceramic or glass baking dish, tilting gently so the entire bottom is evenly coated.

Cut the Cinnamon Rolls: Open both cans of jumbo cinnamon rolls and set the two cream cheese icing cups aside at room temperature. Using a sharp chef knife or kitchen shears, cut each cinnamon roll into 4 to 6 bite-sized pieces. Scatter the cut dough pieces evenly across the prepared baking dish into a snug, uniform layer.

Whisk the Spiced Custard: In a large glass measuring bowl or mixing bowl, vigorously whisk together the eggs, heavy whipping cream, whole milk, maple syrup, vanilla extract, Ceylon cinnamon, and grated nutmeg until completely smooth and frothy.

Pour & Rest the Custard: Slowly and evenly pour the custard mixture over all the cut cinnamon roll pieces, ensuring every crack and dough corner is soaked. Let the dish sit at room temperature for 8 to 10 minutes so the dough absorbs the custard bath.

Bake to Golden Perfection: Bake uncovered in the center rack at 375°F (190°C) for 25 to 28 minutes, until the tops are golden brown, the edges are caramelized and crisp, and the center is just set with a slight tender jiggle.

Glaze Warm & Serve: Remove from the oven. Microwave the reserved cream cheese icing cups for 10 seconds until pourable, then generously drizzle across the piping hot casserole. Let settle for 5 minutes, garnish with fresh raspberries and warm maple syrup, and serve warm.