On a floured surface, unfold one sheet of puff pastry.
Dust the top with a little flour and roll it out into a rectangle.
Cut the rectangle into six equal pieces.
Place a slice of guava paste on each piece.
Brush the edges of each piece with the beaten egg: it acts as glue.
Fold each piece over the filling so it is completely enclosed.
Press the edges firmly with your fingers to seal, then make small cuts along the sealed edge with a knife. These open as the pastry puffs and give the piece its chicharrón shape.
Repeat with the second sheet of pastry.
Arrange the 12 pieces on a baking sheet, leaving space between them so they can puff.
Brush the tops with the remaining beaten egg and sprinkle with sugar.
Put the baking sheet in the oven, preheated to 200 °C (392 °F).
Bake for 20 minutes, or until puffed and deep golden.
Take the tray out and let them cool for about 5 minutes before eating: the guava inside is extremely hot straight from the oven.