Preheat the oven to 400°F and line 2 large baking sheets with parchment paper.

Lay one puff pastry sheet onto each lined baking sheet. Cut each sheet into 6 equal-sized rectangles for a total of 12 rectangles. Leave about ½-inch of space between each rectangle.

In a small bowl, whisk together the egg and milk until smooth. Brush the egg wash over the tops of the puff pastry rectangles, being careful not to get the egg wash on the cut edges. (This can prevent the pastries from puffing up.)

Bake the pastry rectangles for 15-17 minutes, or until they puff up and turn golden brown.

Allow the pastries to cool before assembling (5-10 minutes). Once cooled, separate the top layer from the bottom layer of each puff pastry.

On the bottom half of each pastry rectangle, spread 1 tablespoon of strawberry preserves. Then, using a piping bag or plastic zip bag with the corner cut off, pipe 2 tablespoons of strawberry cheesecake mousse. Top with 5-6 slices of fresh strawberries.

Place the top of the pastry over the sliced strawberries and dust with confectioners' sugar. Repeat the process for the remaining pastries.