Combine the melted butter and Graham crumbs and press into an 8½" (21 cm) springform pan with a disk of parchment paper lining the bottom.
Press to the sides to a height of about 1½" (7 cm)
Place in the refrigerator for about 20 minutes.
In a medium saucepan, melt the butter and stir in the brown sugar until combined.
Add the condensed milk and gently bring to a low boil, stirring constantly.
Simmer gently, stirring continuously until the mixture starts to thicken and caramelize.
Pour into the crust and spread evenly.
Place in the refrigerator for at least 1 hour.
Slice the bananas and place evenly on the caramel layer.
Whip the cream until soft peaks form.
Add the cream over the bananas and trim with shards of grated chocolate.
Refrigerate for a further hour before removing the sides from the pan and serving.