Put the honey, sugar, juice of half a lemon, and water in a large pot and let it boil, uncovered for 8 to 10 minutes until the syrup is thickened. Add rose water and let cool.
Preheat the oven to 356ºF. In a small saucepan, melt the butter and remove the foam that forms on top. In a separate bowl, mix the cinnamon and chopped nuts.
Place a sheet of phyllo dough on the bottom of a large, rectangular baking dish and brush with melted butter. Repeat with three other sheets of dough, then add a third of the chopped nuts in an even layer.
Repeat with 4 more layers of dough brushing each with butter, then add the second third of the nuts. Repeat the process with the rest of the nuts and the dough brushing the last with extra butter.
With a sharp knife, make deep diagonal cuts at the top of the dough making diamond shapes.
Bake the baklava for 30 minutes then lower the oven temperature to 300ºF and bake an additional 45 minutes until the dough is golden brown.
Remove from the oven and pour the syrup over the hot dough making sure that it gets into the cuts. Let cool before serving.