Thaw the Kataifi dough in a fridge overnight, taking it out about 2 hours before working with it and letting it to come to room temperature.
Pulse the nuts in a food processor. Reserve 2 teaspoons of pistachios for sprinkling. In a bowl, combine together pistachios, almonds, sugar, cinnamon and egg white and mix well.
Preheat oven to 350F (175C) degrees.
When the pastry thaws, divide it into 18-22 pieces. The length of one piece in my case was about 10 inches (25cm). Work with one piece at a time and cover the remaining pieces with a damp towel (we have to keep it moist). Brush the surface of a piece with the melted butter and place a heaping tablespoon of the filling at one end of it. Roll it up firmly.
Place all the rolls seam side down in a slightly buttered 9x13-inch baking dish. Brush well with the remaining butter. Bake for 45-50 minutes until golden brown. Allow to cool.
To make the syrup add all the syrup ingredients to a pot an bring to a boil. Simmer for 15 minutes more. Pour the syrup over the rolls. It is important: the syrup has to be hot, while the rolls have to be cool.
Allow the pastry to absorb the syrup. Sprinkle with reserved pistachios and serve. Enjoy!
Store in a covered container at room temperature.