For sweet pastry, beat butter, icing sugar and a pinch of salt using an electric mixer until pale, add eggs and mix. Add flour, mix until just combined, then turn onto a floured surface and form into a disc. Wrap in plastic wrap and refrigerate for 1 hour or until firm. Preheat oven to 180C. Roll out pastry to 3mm thick, line the base and sides of a 25cm-square tart tin (see note), trimming edges to 2cm high and refrigerate for 30 minutes. Blind bake for 15 minutes, remove weights and paper and bake for another 10 minutes or until pastry is golden. Cool, then remove from tin and place on a tray.
Combine sugar and 1/3 cup water in a saucepan and stir over medium-high heat until sugar dissolves. Bring to the boil and cook for 8-10 minutes or until dark-caramel in colour, remove from heat, carefully add cream, butter and 1 tsp sea salt (mixture will spit) and stir. Return to heat and cook for 3 minutes or until smooth, then pour into pastry case and refrigerate for 3 hours or until set.
For ganache, combine chocolate and cream in a saucepan and stir over medium heat until melted. Combine yolks and sugar in a heatproof bowl and whisk over a saucepan of simmering water for 6 minutes or until thick and pale. Remove from heat, fold through chocolate mixture and whisk, using an electric mixer for 6 minutes or until cold. Pour over caramel mixture and refrigerate for 2-3 hours until set. Remove from refrigerator 15 minutes before serving.
Note For a rectangle tart, halve this recipe and use a 11.5cm
x 34cm fluted tart tin.