01 - Preheat oven to 400°F and line a baking tray with parchment paper.
02 - Combine cream cheese, granulated sugar, vanilla extract, and lemon zest in a small bowl. Blend until smooth and creamy. Set aside.
03 - In another bowl, gently toss the diced strawberries with granulated sugar, lemon juice, and cornstarch. Set aside.
04 - Unfold the puff pastry and roll out lightly if needed. Cut into 8 equal squares. Using a sharp knife, score a border about 3/8 inch around each square, taking care not to cut all the way through.
05 - Spoon 1 tablespoon of cream cheese filling into the center of each pastry square, spreading gently within the scored border.
06 - Top each square with 1 tablespoon of the prepared strawberry mixture.
07 - Whisk together the beaten egg and milk. Brush the borders of each pastry with the egg wash.
08 - Transfer the pastries to the pre-lined baking tray. Bake for 18 to 22 minutes, or until the pastries are puffed and golden brown.
09 - Remove from oven and allow pastries to cool slightly on a wire rack.
10 - If desired, whisk powdered sugar, milk, and vanilla extract to form a smooth glaze. Drizzle over cooled pastries before serving.