Crush biscuits into fine crumbs and mix with melted butter and salt. Press into a 9-inch pie dish and chill for 30 minutes.
Heat condensed milk, brown sugar, and butter in a saucepan over medium-low heat, stirring constantly for 10-15 minutes until thickened. Stir in vanilla and salt.
Pour the caramel over the chilled crust, spreading evenly. Refrigerate until set (at least 4 hours or overnight).
Cut bananas into even slices and toss with lemon juice to prevent browning.
Beat heavy whipping cream and powdered sugar until soft peaks form.
Layer banana slices over the set caramel, then spread whipped cream on top.
Sprinkle with grated chocolate, slice, and serve immediately.
Notes
Nutrition information is automatically calculated, so should only be used as an approximation.