Thaw the phyllo dough in the refrigerator if frozen. Trim the sheets to fit your baking dish and keep them covered with a clean, damp kitchen towel while you work to prevent them from drying out.

Pulse the walnuts in a food processor until finely chopped. They should resemble coarse crumbs, not powder. Stir in the cinnamon.

Brush the baking dish with melted butter.

Place one sheet of phyllo in the dish and brush it lightly with butter. Repeat until you have 7 layers.

Sprinkle one-third of the walnut mixture evenly over the phyllo.

Add 5 more buttered sheets of phyllo.

Repeat with another one-third of the walnut mixture and another 5 buttered sheets.

Add the remaining walnut mixture and finish with the final 7 buttered sheets, brushing every layer with butter.

Score the baklava into squares or diamond shapes.

While the baklava bakes, combine the sugar, lemon zest, lemon juice, water, and honey in a small saucepan.

Bring to a boil until the sugar has dissolved completely.

Reduce the heat and simmer for a few minutes until the syrup thickens slightly.