Place all ingredients in a blender and let it sit until the frozen fruit has softened slightly. Pulse on low to break it up into small pieces. Let it sit again and use a spatula to push it down toward the blades. Then pulse again. Repeat this process until it's nice and smooth.
Add some ice if it's not thick enough. Add a bit more milk if it's too thick.
Serve as is: Spoon into a serving dishes and enjoy.
For the iconic dole whip swirl, transfer to a piping bag fitted with an open 1M star tip. Place this in an airtight freezer bag and freeze for 20 minutes. Then swirl it into serving dishes, nice and tall.
Notes
To freeze bananas — Peel them and cut them into slices and place them on a tray lined with waxed paper for 30 minutes. Then transfer to a freezer-safe bag until frozen.If you don't have time for frozen bananas, substitute 2 cups of fresh bananas and 1 cup of ice.