Preheat your oven to 350°F.
Butter the bottom and sides of a 9x13-inch baking dish.
Set aside the prepared dish.
Combine the chopped walnuts and cinnamon in a bowl.
Unroll the phyllo dough sheets.
Cover with a damp towel to prevent drying out.
Brush a sheet of phyllo with melted butter and lay in the dish.
Repeat until you have layered 8 sheets.
Spread a thin layer of walnuts over the sheets.
Continue layering phyllo and nuts, finishing with 8 layers of phyllo on top.
Brush the top with more butter.
Use a sharp knife to cut into diamond shapes.
Bake in the preheated oven for about 50 minutes until crisp and golden.
Meanwhile, make the syrup by boiling sugar, water, honey, and vanilla.
Pour the hot syrup over the baked baklava.