01 - Preheat oven to 400°F and line a baking tray with parchment paper.
02 - In a small bowl, blend cream cheese with granulated sugar, vanilla extract, and lemon zest until the mixture is smooth and creamy. Set aside.
03 - In a separate bowl, toss diced strawberries with granulated sugar, lemon juice, and cornstarch. Set aside.
04 - Roll out the puff pastry sheet and cut into 8 even squares. Using a knife, lightly score a 1/2 inch border around each square, taking care not to slice through the pastry.
05 - Place 1 tablespoon of prepared cream cheese filling in the center of each pastry square and gently spread within the scored border.
06 - Spoon 1 tablespoon of the strawberry mixture on top of the cream cheese in each square.
07 - Combine the beaten egg and milk in a small bowl. Using a pastry brush, lightly brush the borders of each pastry with the egg wash.
08 - Bake for 18 to 22 minutes, or until the pastries are golden brown and puffed. Remove from the oven and cool slightly on a wire rack.
09 - If desired, whisk powdered sugar, milk, and vanilla extract together until a smooth glaze forms. Drizzle over cooled pastries before serving.