Combine bananas, cocoa, salt, sugar and heavy cream in a food processor. Process until mixture is smooth, stopping machine and scraping down sides of bowl as necessary. Transfer to an airtight container, press a piece of plastic wrap on surface of ice cream and freeze until firm enough to scoop, at least 4 hours and up to 2 days.
This was good and REALLY easy but we found it to be bitter because of the unsweetened cocoa. I used 3 Tbsp of sugar to offset the bitterness and still didn't love the flavor. Still, It was a fun treat at the end of a hot day. I plan on playing around with the recipe a bit to see if I can improve on it for our tastes. The frozen bananas made a great base for the ice cream.