Place flour on a work surface and make a well in the centre.
Mix butter and salt into the well and gradually incorporate the flour.
Add iced water and mix until dough just comes together into a ball.
Flatten the dough, wrap in cling film, and refrigerate for 20 minutes.
Roll pastry into a 40cm x 20cm rectangle on a floured surface.
Fold into three, turn 90 degrees, and repeat rolling and folding.
Wrap in cling film and refrigerate for 30 minutes.
Perform two more rolling and folding turns.
Refrigerate for at least 30 minutes before usage.
Simmer sugar and water in a saucepan until dissolved.
Boil syrup to 110°C measured with a sugar thermometer.
Mix ground almonds, egg white, and almond extract in a bowl.
Vigorously stir sugar syrup into the almond mixture and chill until cold.
Preheat the oven to 210°C.
Roll pastry to 3mm thickness and cut four 12cm circles.
Place circles on a baking sheet, score the centres, and brush with beaten egg.
Roll marzipan paste to 5mm thickness and place 11cm circles onto the pastry.
Arrange plum slices over the marzipan in overlapping circles.
Bake for 15-18 minutes until risen and golden-brown.
Melt sugar and star anise in a frying pan until golden brown.
Whisk in butter and cream and bring to a simmer.
Thicken for 3-5 minutes and strain through a sieve into a clean pan.
Serve tart with caramel sauce poured around and a scoop of ice cream.