In a bowl, combine the cold butter cut into pieces, pudding, sugar and flour. RUB everything with your hands into a crumb.
Add vanilla and egg.
Start kneading the dough until it begins to gather into a ball. Wrap the dough in plastic wrap and put it in the refrigerator for half an hour.
Form (I have 25 cm in diameter) lightly sprinkle with flour. The surface on which you will roll out the dough sprinkle with flour. Roll the dough into a circle slightly larger than the shape. Transfer to the mold and distribute evenly, make the sides. Prick with a fork and bake for 10 minutes at 180*C (350*F).
Wash the plums, dry them, cut them in half and remove the stone. Cut each half into slices with a sharp knife so that the halves retain their shape.
Put the cut halves of the plums cut down on the tart alternating the vertical cut with the horizontal one. Mix sugar with cinnamon. Cut the cold butter into small cubes.
Sprinkle the plums with sugar and cinnamon and arrange the butter cubes on top.
Bake in preheated oven to 180*C (350*F) for about 25 minutes. Allow to cool and remove from the mold.