Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish.
Place the cubed Hawaiian rolls in the prepared baking dish, spreading them evenly.
In a large mixing bowl, whisk together the eggs, whole milk, heavy cream, granulated sugar, vanilla extract, ground cinnamon, and salt until well combined.
If using, sprinkle the crushed pineapple and shredded coconut over the bread cubes.
Pour the egg mixture evenly over the bread cubes, ensuring all pieces are soaked. Gently press down with a spatula to help the bread absorb the mixture.
Cover the baking dish with aluminum foil and let it sit for 15 minutes to allow the bread to soak up the custard.
Bake covered for 25 minutes, then remove the foil and bake for an additional 15-20 minutes, or until the top is golden brown and the custard is set.
Remove from the oven and let cool for a few minutes before slicing. Dust with powdered sugar if desired.