Preheat oven to 190ºC and lightly grease a 22cm tart tin.
Lightly roll out pastry and press into tin. Trim off excess and bake tart shell blind for 20–25 min, then remove beans and baking paper and bake a further 10–15 min until golden. Allow to cool. Reduce heat to 170ºC.
Melt chocolate, butter and sugar in a saucepan over a low heat until sugar is dissolved.
Cool mixture for 10 min, then beat in eggs, zest, juice and flour until well combined.
Pour filling into pastry shell; bake 30–40 min or until the filling is just set to the touch.
Allow to cool before removing from the tin. It will rise a bit, but will collapse a little on standing.
To serve, top with sliced orange and a drizzle of golden syrup. Garnish with sprigs of mint.
1 roll (400g) readymade shortcrust pastry, defrosted