Take a rectangular sheet of puff pastry and cut a 1 cm wide strip from each edge. Moisten the edges of the large piece with a little water
and lay the strips along the edge to build up a crust. Prick the base all over with a fork and bake in a 200°C oven for 15 minutes,
until puffed up and slightly golden. Remove from the oven, and turn the oven down to 180°C. For the filling, mix together 20g butter,
70g sugar and a beaten egg until smooth, then add 90g ground almonds, ½ tsp vanilla extract and ½ tsp almond extract and mix together
to form a thick paste. Spread this onto the cooled pastry case. Halve and destone some plums, and cut into slices. Add these to the top
of the frangipane and bake in the oven for about 30 minutes. Remove and when cooled, brush on a glaze made from 3 Tbs apricot jam mixed
with a couple tsp hot water. Serve with a spoon of crème fraîche.