01 - Combine mashed bananas, whole milk, heavy cream, sweetened condensed milk, granulated sugar, vanilla extract, and salt in a blender. Blend until completely smooth.
02 - Pour the blended mixture into the Ninja Creami pint container. Seal tightly and place upright in the freezer for at least 12 hours or overnight until fully solidified.
03 - In a bowl, stir together graham cracker crumbs, melted unsalted butter, and brown sugar until the mixture has the consistency of damp sand. Set aside.
04 - After the base is frozen solid, insert the pint into the Ninja Creami and run the 'Ice Cream' cycle until smooth and creamy.
05 - Using a spoon, create a 1-inch well in the center of the ice cream. Add the prepared graham cracker mixture to the well.
06 - Reinsert the pint and run the 'Mix-In' function on the Creami to evenly incorporate the graham cracker swirl throughout.
07 - Scoop the finished ice cream into bowls. Top with whipped cream and sliced bananas as desired. Serve immediately for optimal texture.