Line two 18 x 13 x 1-inch baking sheets with parchment paper or non-stick liners.
Prepare the filling: Beat together cream cheese, sugar, lemon juice and orange blossom water until light and fluffy.
On a lightly floured surface, roll out the first sheet of dough into a 12-inch, 1/8-inch-thick square.
Using a small knife or pastry wheel, cut dough to measure 9 squares, 4 inches by 4 inches each. Add 1 tablespoon of guava jam or paste topped with 1 tablespoon of cream cheese filling, off-center, to each square. Brush the egg wash around the filling.
Fold the square of dough over itself to form a triangle and weld the edges. Lightly brush the top of each triangle with egg wash.
Transfer filled pastries to a prepared baking sheet and refrigerate until firm, 20 to 30 minutes. Repeat with the rest of the dough.
While the pastries are cooling, preheat the oven to 400 degrees.
Prepare the icing: Combine the sugar and water in a small saucepan. Simmer over medium heat until the sugar has dissolved, about 2 to 3 minutes. Remove from heat and let cool.
Place the baking tins in the preheated oven and bake until lightly browned, 20 to 25 minutes.
Rotate the trays halfway to make sure the pastries are baking evenly.
Remove the pastries from the oven and brush them with a simple syrup icing. Let the pastries stand for 10 minutes on a baking sheet, then transfer to cooling racks.
To note: If using guava paste, cut the guava into pieces and pass it in a blender or food processor with 2 teaspoons of freshly squeezed orange or lime juice until smooth. Use as directed.