Cooking oil, to grease
2 sheets frozen shortcrust pastry, partially thawed
240g dark chocolate, finely chopped, plus extra grated chocolate, to serve
375ml cups cream
2 Tbsp unsalted butter
3⁄4 cup caster sugar
Juice of 1⁄2 lemon
Generous pinch sea-salt flakes
3 ripe bananas
Double cream, to serve
Preheat oven to 180°C fan- forced (200°C conventional). Grease a 22 x 4cm deep loose-based tart tin.
Join pastry sheets along 1 edge, pressing firmly to seal. Press into base of prepared tin. Trim edges then chill pastry shell for 15 minutes. Line shell with foil and fill with baking beans or uncooked rice. Bake for 20–25 minutes or until deep golden. Discard beans or rice. Place tin on a wire rack to cool.
Meanwhile, put chopped chocolate in a medium heatproof bowl. Combine cream and butter in a medium saucepan and bring to the boil over a medium heat. Pour over chocolate, stirring, until chocolate has melted and mixture is smooth.
Put sugar in a small saucepan. Heat over a high heat for 3–5 minutes or until sugar melts and is a deep-brown caramel. Remove from heat. Stir in chocolate mixture, lemon juice and salt (take care as mixture may spit). Puree with a stick blender until very smooth.
Slice bananas. Arrange over base of tart. Pour chocolate mixture over top. Chill for 2–3 hours, or overnight, until firm. Remove tart from tin. Serve sprinkled with extra chocolate and with cream on the side.