If you're using fresh pineapple, peel and core the fruit, and then cut into chunks. (Save a few pieces with the peel on for garnish.) Place the pineapple chunks onto a baking sheet and spread into an even layer.
Freeze for 1 hour 30 minutes until the pineapple is frozen. This will take the place of ice in your blended cocktail.
When you're ready, put the frozen pineapple into a blender. Pour in the half-and-half and rum. Cover the blender and puree until smooth and creamy.
Pour into poco glasses and garnish with a pineapple wedge, cherry, and some coconut flakes. Serve immediately.
Notes
You can prep and freeze the pineapple ahead of time. Once the pineapple is frozen, transfer it to a Ziploc bag and store it in the freezer until you're ready to use it.