Combine heavy cream, whole milk and sugar in a large stock pot. Heat over medium high heat until your mixture starts to bubble.
In a large bowl, whisk your egg yolks.
Slowly pour about 1/2 cup of the cream mixture into your egg yolks, while whisking the mixture vigorously.
Pour another 1/2 cup, and then another half cup whisking while adding them, and after each addition.
Pour the egg mixture back into the sauce pan with the remaining cream mixture.
Continue to heat for about 5 minutes until the mixture is thickened enough to coat the back of a spoon.
Strain mixture into a large bowl.
Add about 1 cup of custard to a blender or food processor with the bananas. Puree until smooth.
Pour back in with the rest of the custard mixture.
Mix in the vanilla.
Put the bowl into an ice bath (a larger bowl filled with ice and water) and allow to set to chill for about 10 minutes, stirring occasionally.
Cover bowl with plastic wrap and place in the fridge for about 2 hours, up to overnight.
Pour mixture into an ice cream maker and mix according to maker instructions.
Add in chocolate chunks and walnut chunks and allow to mix about 5 minutes until mixed throughout the ice cream. Enjoy now for soft serve ice cream.
Scoop ice cream into a bread loaf pan and cover with plastic wrap.
Freeze about 6 hours up to overnight before serving if you want scoopable ice cream.