Preheat the oven to 400 degrees F and line 2 large baking sheets with parchment paper and set aside.
Add the sliced strawberries, cornstarch, and granulated sugar to a medium bowl and toss to combine, let sit until ready to use.
Unfold the two puff pastry sheets and use a rolling pin to gently roll them out to smooth out the creases, but don’t press hard, it’s okay if some remain.
Use a pizza or pastry cutter to cut each of the sheets into 4 equally-sized squares.
Fold over the corners of each of the squares about an inch to create an octagon. Feel free to wet your fingers to help the dough stick together. Transfer the pastries to baking sheets, placing 4 on each.
In a large bowl or stand mixer fitted with a paddle attachment, cream together the cream cheese and sugar until smooth.
Add in the egg yolk, vanilla, and salt and beat until fully combined.
Use a medium cookie scoop to scoop the cream cheese mixture onto the center of the puff pastries.
Beat together the egg and water to create the egg wash and brush all over the pastry around the cream cheese mixture.
Use an offset spatula or the back of a spoon to slightly flatten the dollops of cheese and spread it out.
Distribute the strawberry mixture evenly on top of the cream cheese mixture.
Bake one baking sheet at a time for 18 to 20 minutes each, placing the other in the fridge while the first one bakes.
Let cool slightly and dust with powdered sugar before enjoying.
It’s really important that puff pastry stays cold (but not frozen) for the best baking results. Puff pastry should not be out of the cold for more than 30 to 40 minutes, this is why the second baking sheet needs to go back in the fridge while it waits to bake.
Puff pastry can be thawed in the fridge overnight for best results.
Adding sugar and cornstarch to the berries helps pull out the juices while also keeping them intact making for a better and more flavorful baked berry.
You do not want to apply the egg wash under the cream cheese mixture because it will impact cooking. Only brush it on top.
Reheat leftovers in the microwave for 15-seconds.
Only bake one sheet at a time, otherwise, one usually overcooks before the other fully cooks.