Preheat the oven to th.7 (210°C).
Butter a 26 centimeter pie dish and line it with the pastry. Prick the bottom with a fork and sprinkle with ground almonds mixed with 50 g of sugar and cinnamon powder. Slide into the oven and cook for 10 minutes.
Cut the quetsches and Mirabelle plums in half and pit them. Arrange them on the pre-baked pie shell, sprinkle with the remaining sugar, sprinkle with plum brandy and bake again for 20 minutes.
Leave the pie to cool before unmolding it and just before serving, dust with icing sugar.
Serve with heavy cream or Chantilly, also flavored with aged plum.