Preheat oven to 350˚F. Line a 9”x13”, rimmed sheet pan with parchment and set aside.
In a mixing bowl, combine nuts and cinnamon and toss together. Set aside.
Brush butter onto parchment and layer 10 sheets of phyllo dough into the pan, brushing butter between each layer.
Sprinkle half the nut mixture over the phyllo and repeat step one with 5 more sheets of phyllo.
Dot the entire surface with pieces of brie and continue to layer 5 more sheets of phyllo and butter.
Sprinkle remaining nut mixture over the phyllo and finish by layering the remaining 10 sheets of phyllo and butter. Cut 1 inch strips into baklava, in a diagonal pattern each way, creating diamond shaped pieces.
Bake for about 1 hour or until golden brown.
While the baklava bakes, combine sugar and honey in a small saucepan and bring to a boil until sugar dissolves. Remove from heat and allow to cool.
Remove baklava from oven and pour sugar mixture over pan. Allow mixture to soak in and sit for about 1 hour. Top with finely chopped pistachios and serve.