Thaw puff pastry according to package directions.
Preheat oven to 400 degrees.
Roll out the puff pastry and cut into a circle.
Combine the blueberries, 3 tsp. sugar, cornstarch, and the juice of half of the lemon in a bowl and mix.
Cream together the cream cheese, 2 tsp. sugar, egg yolk and half the zest in another bowl.
Spread the cream cheese mixture on dough to within a few inches of edge. Top with the blueberry mixture.
Fold the dough up and over the berry mixture, pinching the dough to secure. Brush with egg white and dust with turbinado sugar if desired.
Bake at 400 degrees for 30 minutes. Allow to rest for at least 10 minutes. Top with second half of lemon zest and serve.