Finely chop 100 g dark chocolate and melt it with 40 g butter until smooth.

Mix the melted chocolate mixture with 30 g roasted hazelnuts, 90 g bran flakes, and a pinch of sea salt.

Press the crumb mixture firmly into the tart tin to form an even base and sides.

Chill the tart case in the refrigerator until firm, about 20 minutes.

Heat 35 g sugar in a saucepan until it melts into an amber caramel.

Whisk 7 g butter into the caramel, then gradually whisk in 65 ml double cream.

Remove the caramel from the heat and stir in 1 tablespoon white miso.

Transfer the miso caramel to a bowl and let it cool until thickened but pourable.

Finely chop 60 g milk chocolate and 90 g dark chocolate, then place them in a heatproof mixing bowl.

Heat 200 ml double cream in a saucepan until steaming and just beginning to simmer.

Pour the hot cream over the chopped chocolates and let it stand for 1 minute.

Stir the ganache gently until all chocolate is melted and the mixture is glossy.

Pour the chocolate ganache into the chilled tart case and level the surface.

Drizzle the cooled miso caramel over the ganache and swirl it with a knife.

Refrigerate the tart until the ganache is set, about 2 hours, then slice and serve.