Preheat the oven to 170 degrees Celsius (325 Fahrenheit).
In a mixing bowl, add the chopped walnuts, sugar and cinnamon and mix well.
Lay one pastry sheet on the work surface, brush it well with melted butter and fold it in half.
Lay another sheet on top of it, brush it melted butter, and fold it in half as well.
Add 3 tablespoons of the walnut mixture along one edge.
Fold the short sides inward over the filling, then roll up tightly from the filled edge, burrito-style, enclosing the walnut mixture and sealing the ends as you roll.
Repeat with the rest of the pastry and walnut mixture.
Cut each roll in 3 equal parts, and arrange them onto a baking tray.
Bake for 40-45 minutes or until golden and crispy.
Meanwhile, make the syrup.
Mix the water, sugar, lemon juice, honey and cinnamon stick on a pan set over a medium heat.
Mix well to dissolve the sugar, and allow it to simmer for 4-5 minutes.
Remove it from the heat and allow it to cool down.
Once the rolls are ready, remove the tray from the oven, and pour the cold sryup over the rolls.
Leave them to cool down completely, so that the rolls can soak up the syrup.