Preheat the oven to 180 C / Gas 4. Line a baking tray with baking parchment.
Roll out the pastry and cut into 3 to 4 circles of about 25cm diameter. Separate the filling in 3 to 4 portions and place a generous dollop of cream cheese and one slice of guava paste on each pastry round, slightly to one side.
Brush beaten egg around the edges, then fold the pastry in half and seal it. Place the pastries on the baking tray and brush the tops with beaten egg.
Bake them in the oven for about 30 minutes, or till golden brown. Cool slightly and enjoy warm or at room temperature.