For the banana ice cream, cream the plain yolks and sugar in a food processor. Chop the chocolate and heat with the milk. Stir to dissolve the chocolate. When completely dissolved, slowly pour into the yolk mixture.
Remove mixture from food processor and pour into saucepan. Heat again while stirring (do not boil!) until it takes on a thick consistency. Pour back into bowl and let cool slightly.
Peel bananas, mash with a fork, sprinkle in cinnamon and stir into cooled chocolate mixture. Whip the cream until slightly stiff and fold in carefully.
Freeze the mixture for the plain banana ice cream for at least four hours until well sealed, then churn into ice cream in the ice cream maker according to instructions.