Preheat your oven to 400°F/200°C. Line a baking sheet with parchment paper.
In a mixing bowl, beat the softened cream cheese, lemon zest, sugar until fully blended, then and vanilla extract and egg yolk, continue to beat until the mixture is creamy and well combined. Put mixture in a piping bag.
Note: If you don’t have piping bags at home. No worries! Fill a zip lock baggie with the cream cheese mixture and snip the corner in place of a piping bag.
Lay out the puff pastry on a lightly floured surface to a 12-inch square. Using a heart cookie cutter 5”/8cm size. Cut out approximately 8 hearts from two sheets of puff pastry.
Transfer the puff pastry hearts onto the lined baking sheet. Use a smaller heart cutter 2.5”/6.5cm in size to create a slight indentation, being careful not to cut through. This will allow the pastry to rise along the outside edges. Tip: I use the dull side on the smaller heart to ensure I don’t cut through.
Now egg wash the outside edges only, outside the lines of the smaller heart. Generously sprinkle with castor sugar along the outside edges.
Pipe a layer of cream cheese mixture in the center of each puff pastry heart, following the inside indentation of the smaller heart only. Leave the outside borders free from cream cheese so they can rise.
Place 2 strawberry slices onto the cream cheese mixture, following the pattern of the heart.
Optional: Cut “strawberry leaves” with a fondant flower cutter with the remaining puff pastry. Cut the flower shape in half to create leaves, add the leaves to the top of every strawberry tart and egg wash.
Bake for 15-18 minutes, or until the pastry is golden brown and puffy.
Allow the baked pastry hearts to cool on the baking sheet for few minutes before transferring them to a wire rack to cool completely.
Finally dust the pastries with powdered sugar before serving.