Chop banana freeze in chunks. I keep frozen chopped banana on hand in the freezer for smoothies and frozen custard so it's ready when I want to make it.
Chop mango and freeze in chunks. You can buy frozen mango. If you do, let it sit out for 15 minutes before putting in food processor because it tends to be really frozen and hard (compared to fresh mango).
Put frozen banana and mango chunks into a food processor with rest of ingredients and blend until smooth and creamy.
Eat immediately for soft serve or freeze for harder ice cream.