01 - Combine mashed bananas, whole milk, heavy cream, sweetened condensed milk, granulated sugar, vanilla extract, and salt in a blender. Blend until fully smooth.
02 - Pour blended mixture into the Ninja Creami pint container. Seal and freeze upright for at least 12 hours, preferably overnight.
03 - Mix graham cracker crumbs, melted butter, and brown sugar in a small bowl until the texture resembles wet sand. Set aside.
04 - Once frozen, insert the pint with ice cream base into the Ninja Creami and process on 'Ice Cream' mode.
05 - After the initial cycle, create a 1-inch wide well in the center. Spoon graham cracker mixture into the well.
06 - Reinsert pint and run the 'Mix-In' function to evenly distribute the graham cracker swirl.
07 - Scoop into bowls. Garnish with whipped cream and additional banana slices if desired. Serve immediately for optimal creaminess.