Start with blind baking the puff pastry.
Roll out the puff pastry (I used a shop bought one) onto the baking parchment and fit it into a round baking tray of 26cm in diameter. There should be some extra pastry around the margins of the tray that is best to fold gently, creating a nice little edge.
Prick the pastry with a fork and bake in the preheated oven at 180 C (temperature for a non fan assisted oven, otherwise set the temperature to 170 C) for around 15 minutes. The pastry should become light golden colour.
Set aside and wait until it cools down.
Once the pastry has cooled down, tightly arrange the plum pieces starting with the outer circle pressing the plums into the edges.
Mix the sugar with the cinnamon and sprinkle it evenly on the plum pieces.
Cut the butter into small slices and sprinkle over the tart.
Bake in the preheated oven at 180 C for 40 minutes until the pastry becomes golden in colour.
Best served still warm with a dollop of crème fraîche or vanilla ice cream.