Preheat the oven to 350°F. Grease a baking pan that fits the package of Hawaiian rolls with non-stick spray. Set it aside.
In a small bowl, mix the melted butter, granulated sugar, and cinnamon powder.
Slice each Hawaiian roll in one direction without cutting all the way through, then turn 90 degrees and cut in the other direction.
Place the sliced rolls in the prepared baking pan. Use a small spoon to drizzle the cinnamon butter mixture evenly into the cut openings.
Bake for approximately 20 minutes, until the rolls are nicely toasted.
Remove from the oven and transfer to a wire rack to cool. While still warm, drizzle the glaze over the top. Allow the glaze to set for a few minutes before serving.
To make the glaze, combine the powdered sugar, 1 tablespoon of milk, vanilla extract, and salt. The mixture will be very thick. Add an additional 1-3 teaspoons of milk to achieve a thick but pourable consistency. If the glaze becomes too thin, add more powdered sugar to thicken it.