Preheat the oven to 350°. Spread the coconut on a baking sheet and cook until lightly toasted about 4-6 minutes. Remove from oven and set aside.
In a small bowl combine ½ cup milk and cornstarch. Whisk together.
In a medium saucepan combine the rest of the milk, sugar and cream of coconut and salt. Bring to a simmer over medium heat, stirring constantly until the sugar is dissolved and the milk is just starting to steam -- do not boil.
Whisk the cornstarch mixture into the hot milk mixture and stir constantly over medium heat until pudding begins to thicken. Remove from heat and stir in the butter and rum to combine.
Pour pudding into a serving dish or individual ½ cup ramekins and refrigerate 3-4 hours until chilled.
About 1 hour before serving, make the fruit salad. In a small bowl, combine the mango, blueberries and strawberries. Sprinkle with sugar and rum and toss to coat. Let the fruit sit for at least 20-30 minutes until the sugar is dissolved.
To serve, spoon macerated fruit over the pudding and sprinkle with a tablespoon or so of toasted coconut. Enjoy!