For the hard-boiled eggs, place them in a saucepan with room-temperature water. Place the saucepan over high heat. When it comes to a rolling boil, start counting 8 minutes. Then transfer the eggs to a bowl with ice to stop the cooking process. Peel them and cut them in quarters.
Divide the dough into 6 equal portions. Roll them out as round as you can until the dough is 2-3mm thick. Then cut it round by using a 20cm/8in diameter dish as a template, cutting around it with a knife.
Place about 4-5 tablespoons of filling at the centre and slightly to one side of the empanada. Place an olive on top and ¼ of an egg.
Beat the egg and water from the egg wash and use it to paint the edge of the empanada. Fold it in half. Stick it well and try to remove all the air. Then, fold the edges in and the front upwards. This will give you a rectangular empanada. Une your index finger and press on all corners of the empanada to seal them.
Place the empanada on a baking tray lined with baking paper and paint with the egg wash. Repeat with all the empanadas.
If you have leftover dough you can bring it together using wet hands and roll it out again.
Bake the empanadas in a preheated oven at 200°C/400°F for 20-25 minutes or until they're golden on top and underneath.
Serve them hot.