Add 1 cup heavy cream and bananas to a blender, process until smooth. Pour through a mesh strainer into a large bowl.

In a medium saucepan over medium heat, combine whole milk, remaining 1/2 cup heavy cream, brown sugar, salt and vanilla. Stir until sugar is dissolved and mixture is steaming.

Whisk yolks in a small bowl. While whisking continuously, slowly pour 1 cup hot liquid into yolks. Transfer mixture back to saucepan. Cook over medium heat until mixture coats the back of a wooden spoon or spatula. Pour through mesh strainer into banana-cream mixture. Cool over an ice bath to room temperature. Cover and chill thoroughly, at least 4-6 hours or overnight.

Meanwhile, prepare your favorite brownie recipe. Cutting 1 1/2 cups worth of 1/2-inch pieces. Arrange in a single layer on small baking sheet. Freeze until firm, roughly 1-2 hours.

Churn ice cream according to manufacturer's directions. Spoon churned ice cream into a freezer safe container, scattering brownie chunks throughout. Freeze until solid, at least 4-6 hours.