01 - Combine mashed bananas, whole milk, heavy cream, sweetened condensed milk, granulated sugar, vanilla extract, and salt in a blender. Process until the mixture is completely smooth.
02 - Pour the blended mixture into the Ninja Creami pint container. Seal tightly and freeze upright for at least 12 hours or overnight to ensure a solid freeze.
03 - In a small bowl, mix graham cracker crumbs with melted unsalted butter and brown sugar. Blend with a spoon until the mixture has a wet, sandy consistency. Set aside.
04 - Place the frozen pint in the Ninja Creami and run the ice cream cycle until creamy and aerated.
05 - Create a 1-inch well in the center of the ice cream. Add the prepared graham cracker crumble into the well.
06 - Return the pint to the machine and process using the 'Mix-In' function until the graham swirl is fully incorporated.
07 - Scoop the finished ice cream into bowls. Top each serving with whipped cream and sliced bananas as desired. Serve immediately for optimal texture.