Preheat the oven to 400℉ and line a baking sheets with parchment paper.
Add the cream cheese, powdered sugar, cinnamon, and vanilla extract to a medium bowl. With electric mixer, beat until smooth and creamy. Set aside.
To prepare the plums, cut each in half, remove the stone, and cut into thin slices (about ⅛").
Lay the cool but thawed puff pastry sheet on a lightly floured surface. Smooth the fold lines and then cut 9 circles using a 2 ½“ round cookie cutter. Then use a smaller cutter or glass to score an inner circle on the pastry, but don't cut all the way through. With a fork, prick the inner circle of each pastry.
Spoon or pipe small amounts of the cream cheese mixture into the center of each circle and spread slightly. Arrange plum slices ontop and press down gently into the cream cheese mixture.
Brush the edges of the pastries with milk or cream and then sprinkle the cinnamon sugar over the top of each tart.
Bake for 10-15 minutes or until the edges of the pastry are beautifully golden brown. Carefully transfer to a cool rack and let cool for a few minutes before serving.
Notes
Plums: I'm using small Italian plums in this recipe. The quantity may vary depending on the size and variety of the plum you are using. Using a very sharp knife, slice them as thin as possible and place 3 slices on each tart.