Add strawberries, sugar, cornstarch, and salt to a medium-sized pan. Cook over medium heat for 10-12 minutes while stirring. Once the filling is bubbly and thickened, remove from heat and let it cool.
Line two baking sheets with parchment paper and set aside.
Sprinkle the flour on a clean counter or cutting board. Roll out the pie doughs on the floured surface so that they are ⅛ to ¼ inch thick.
Using a 4-inch round cookie cutter (or any round object that is easy to trace), cut out 18 rounds of dough.
Place 9 of the rounds of dough on the baking sheet.
Place a slice of brie cheese onto each dough round. Dollop a teaspoon of jam filling on top of the brie, spreading it evenly across the middle of the pie base.
On the remaining dough rounds, use a knife to cut a small “X” or a star cookie-cutter to cut out a star shape in the middle to allow for ventilation when baking.
Place a second round of dough on top of each round with filling, creating a sandwich. Press down the edges to seal.
Place the completed pies in the refrigerator for 20 minutes.
While the pies are refrigerating, whisk the egg with water to create an egg wash.
Remove the pies from the refrigerator. Using a fork, crimp the edges around each pie.
Lightly brush the top of each pie with the egg wash.
Bake the pies for 20-25 minutes until they are puffed up and golden. Let them cool slightly and enjoy!