Preheat the oven to 350°F.
Melt the butter and chocolate squares together in a large microwave-safe bowl for 2 minutes, stirring every 30 seconds, until fully melted.
Allow mixture to cool slightly, then stir in sugar.
Beat in eggs and vanilla until combined.
Stir in flour and cinnamon, then fold in 1-1/2 cups chopped walnuts.
Set brownie batter aside.
Unroll phyllo dough on a clean surface.
Place a 9×13-inch baking dish in the center and cut phyllo to fit.
Cover phyllo with damp cloth to prevent drying.
Melt 1 cup butter.
Brush bottom and sides of dish with butter.
Place one phyllo sheet in dish and brush with butter; repeat 6 times.
Spread half of brownie batter over phyllo.
Layer 6 more phyllo sheets, brushing each with butter.
Spread remaining brownie batter over this layer.
Top with remaining phyllo sheets, brushing each with butter.
Cut unbaked baklava into 24 squares.
Brush top with butter and sprinkle remaining walnuts.
Bake 30-35 minutes until golden and crisp.
Remove from oven and drizzle with 1 cup honey.
Let set 3 hours.
Drizzle remaining 1/2 cup honey before serving.