In a saucepan combine half and half, sugar and vanilla bean seeds and pod. Bring to a boil. In a bowl whisk egg yolks. While whisking stream in about 1/3 of hot cream mixture. Return saucepan to heat and whisk egg mixture into sweetened cream. Continue to stir over medium heat until the mixture thickens and comes just to the boil. Strain custard into a bowl over ice. Transfer to a prepared ice cream maker. Follow manufacturer's instructions. Add bananas just before freezing is finished. Freeze until firm.