Preheat oven to 325 degrees F. Butter a 9 by 13" rectangular baking pan on the bottom and sides. (Don't use part of the butter in the recipe). In a large bowl, combine the chopped walnuts and cinnamon until coated. Set aside.

First, make your honey syrup as it needs time to cool while your baklava is being prepared and baking. In a medium saucepan, combine the granulated sugar, water, honey, and lemon juice over medium-high heat. Bring to a boil until sugar dissolves, then reduce heat to medium-low and boil for 4 minutes without stirring. Remove from the heat and let cool.

Unroll the phyllo dough and trim to fit the pan if necessary. Place one damp towel down on the counter, put the phyllo dough on the towel, and cover with another damp towel. Keep the phyllo covered at ALL times, even if it is only 15 seconds. Phyllo dries out very quickly and needs to be kept under a moist towel constantly.

Place one phyllo sheet into the bottom of the pan. Brush with melted butter using a pastry brush. Repeat 9 times for a total of 10 buttered sheets in the pan. Spread with 3/4 cup of the nut mixture. Add 5 more buttered sheets, buttering and layering one at a time, then top with another 3/4 cup of nut mixture. Repeat four times - 5 more sheets, 3/4 cup nuts, etc.

Lastly, finish off with 10 buttered and layered phyllo sheets. Using a sharp serrated knife, cut the baklava gently and carefully into strips, then cut diagonally into diamonds.

Bake for 1 hour - 1 hour 15 minutes or until baklava is browned on top and crisp. Remove from the oven and immediately pour the cooled honey syrup evenly over the top. The baklava will sizzle, bubble and may pop - this is great! Allow mixture to come to room temperature and cool completely, then cover loosely with a dry tea towel and let set for at least 6 hours, preferably overnight, before serving. It needs time for the honey syrup to penetrate the layers fully.