Cut the plums in half, remove the stone then slice the flesh into thin half-moon shapes.
Mix together the frangipane cream.
Unroll the pastry. With a pastry cutter or a mug, stamp out 6 circles (10 cm in diameter) and place theses in a baking sheet lined with baking paper.
Put another, 8cm in diameter, mug or cutter in the middle of the pastry circles, and gently push down to create a 1cm rim. Brush the rim with egg. Using a fork, prick the inner circle a few times, then spread some frangipane evenly within the inner circle.
Arrange the plum slices on top of the almond cream, don’t let them go over the line, onto the rim.
Heat the jam with 1-2 Tbsp of water and brush the top of the plums with the jam.
Rest the baking sheet in the fridge for 15 minutes.
Turn on your oven to 200°C.
Take the tarts out of the fridge and bake them for 15- 20 minutes, until golden brown.
Let them cool on a wire-rack before serving.