Combine the bananas, lemon juice, cream and sugar into a food processor and combine for 1 minute until smooth.

Remove ice cream bowl from the freezer and place into ice cream machine. Transfer banana mixture to the frozen bowl and add the walnuts, chocolate chunks and 1/2 the brownie bits. Freeze according to the manufactures directions. Carefully stir in remaining brownie bits at the end.

Remove ice cream from the bowl and place into a freezer safe container for at least 2 hours before serving.