Place the plums in a bowl, sprinkle with Armagnac and leave to stand overnight. Heat the milk, sugar and butter until the butter has melted and the sugar has dissolved. Dab plums dry. Dust with 1 tablespoon of flour. Mix eggs and 125 g flour. Slowly pour in the milk mixture and mix well.
Pour the dough into a greased ovenproof dish (23 x 30 cm). Spread plums on top. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 45 minutes. Remove from the oven, place on a cake rack and let it cool down. Dust with icing sugar and cut into 9 pieces. Arrange on plates
Waiting time 12 hours