Preheat the oven to 350°F. Add the nuts and cinnamon to a medium bowl and mix together. Unroll both tubes of phyllo dough on a clean surface, cover loosely with saran wrap and a damp dishcloth so the dough doesn’t try out.
Evenly sprinkle the top of the buttered 8th sheet with 2 to 3 tablespoons of the nut mixture. Lay another two sheets on top and brush with butter and then add more nuts. Repeat the layers every 2 sheets until you have just 8 sheets left, adding those two at a time and only brushing with butter. Cut 4 rows down the length of the pan and then cut diagonally all the way down and across the pan for a traditional baklava prep.
Bake for 45 to 50 minutes. With 30 minutes left to bake, make the syrup. Remove the baklava from the oven and immediately pour the sauce over the entire pan, let set and cool.