Prepare an ice bath by adding a good amount of ice cubes to a large bowl and then adding some cold water. Set aside.

Warm the milk, sugar, 1 cup of the cream, and salt in a medium saucepan. Stir until sugar dissolves. Remove pan from heat.

In a large bowl, combine remaining 1 cup of cream and chocolate malt powder. Set a mesh strainer over the top of the bowl and set aside.

In a medium bowl, whisk together the egg yolks. Slowly pour the warmed mixture into the egg yolks, whisking constantly. Then scrape the warmed egg yolks back into the saucepan and place over medium heat. Stir the mixture constantly with a heatproof spatula, scraping the bottom as you stir, until the mixture thickens and coats the spatula. It's now a custard.

Pour the custard through the strainer and stir it into the cream and malt powder. Add the vanilla and then set the bowl in the prepared ice bath. Stir the custard until it is no longer warm. Then place the custard in the refrigerator to chill thoroughly, about an hour.

Just before you are ready to churn the custard, combine the mashed banana with lemon juice. Place mixture in refrigerator.

When ready to churn the custard, pour it into your ice cream maker and freeze according to the manufacturer's instructions. When the ice cream is thickened and mostly finished, stir in the cold banana mixture and churn for a few more minutes to completely combine.