Preheat your oven to 400°F (200°C).
Prepare the cream cheese filling by mixing cream cheese, sugar, vanilla extract, and egg in a bowl until smooth.
Roll out the puff pastry on a floured surface to smooth out any creases and make it easier to shape.
Cut the pastry into squares and place them on a lined baking sheet.
Spoon the cream cheese mixture onto the center of each pastry square.
Top the cream cheese filling with sliced strawberries and sprinkle with cornstarch and lemon juice.
Fold the corners of the pastry squares towards the center to create a pocket, pinching edges to seal.
Brush the pastries with an egg wash for an attractive shine.
Bake for 20-25 minutes until the pastry is golden and puffed up.
Let the pastries cool for a few minutes before serving.