Carefully pull apart the sheets of dough and cut them to the size of the baking pan. Cover with a damp cloth. Chop or grind the nuts (walnuts and almonds), but not too finely. Beat the egg whites until stiff, and stir in the honey, nuts, cinnamon and rosewater.
Preheat the oven to 200°C (approximately 390°F) convection.
Brush the baking pan with butter, and alternately fill pan with a layer of the dough, then the nut mixture, until there are about 4-5 layers. Make sure to brush each sheet of dough with plenty of butter and finish with a sheet of the dough.
Bake in preheated oven until golden brown, or about 30 minutes.
Meanwhile, mix the sugar with 250 ml (approximately 1 cup) water and bring to a boil, and let boil for about 1 minute. Remove from heat, let cool slightly and stir the lemon juice into the sugar water.
Take the finished baklava out of the oven and, while still hot, gradually soak with the syrup. Let cool. To serve, cut into pieces and serve garnished with currants.