Line a 9×9-inch pan with parchment paper.
Combine graham cracker crumbs, melted butter, condensed milk, and vanilla until mixed.
Firmly press mixture into pan bottom.
Sprinkle white chocolate chips, marshmallows, and festive sprinkles on top.
Refrigerate for at least 2 hours until set.
Lift from pan, slice into squares, and enjoy chilled.
