01 - Preheat oven to 400°F and line a baking tray with parchment paper.
02 - Blend cream cheese, granulated sugar, vanilla extract, and lemon zest in a small bowl until smooth and creamy. Set aside.
03 - Combine diced strawberries with sugar, lemon juice, and cornstarch in a separate bowl. Mix gently and set aside.
04 - Roll out puff pastry sheet and cut into 8 equal squares. Score a 1/3-inch border around each square without cutting through.
05 - Spoon 1 tablespoon of cream cheese filling into the center of each square and spread within the border. Top with 1 tablespoon of strawberry filling.
06 - Brush pastry borders with egg wash prepared by mixing beaten egg and milk.
07 - Place pastries on the prepared baking tray and bake for 18 to 22 minutes until puffed and golden brown.
08 - Transfer pastries to a wire rack and allow to cool slightly.
09 - For the optional glaze, whisk powdered sugar, milk, and vanilla extract until smooth. Drizzle over cooled pastries before serving if desired.