In a medium bowl, mix together graham cracker crumbs and melted butter until well combined. Press mixture into the bottom and sides of a 9-inch deep-dish pie tin. Bake for 10 minutes until golden brown and fragrant. Let cool.
In a large nonstick skillet, melt the butter and sugar, stirring constantly.
Add the sweetened condensed milk and cook, stirring well, until the mixture browns and comes to a boil. Allow the mixture to boil for at least one full minute before taking it off the heat.
Spread the caramel over the cooled base, and chill for at least one hour, or until you are ready to serve it.
Cut bananas into 1/4-inch slices, and spread over the toffee surface.
In a large chilled bowl, use a hand mixer or whisk to whip together the cream and brown sugar until stiff peaks form. Spread cream all over the surface of the pie.
Drizzle with toffee caramel and chocolate sauce.
Using a knife, ripple the sauces through the whipped cream.
Cut and serve slightly chilled. Store covered in the fridge for up to 3 days.