Preheat the oven to 350 degrees. Line a 9-by-13-inch baking dish with foil, leaving a 3-inch overhang; butter the foil. In a large saucepan, melt 3 sticks butter over medium. Cook, stirring often, until browned bits form, 4 to 5 minutes. Remove from the heat; add the sugar, vanilla and salt. Using an electric mixer on medium speed, beat until glossy, about 1 minute. Add the eggs; beat on low until blended. Add the cocoa powder, flour, espresso powder and 2 tsp. cinnamon; beat on low just until blended. Scrape into the baking dish.
Bake until a toothpick inserted into the center comes out with a few moist crumbs attached, about 35 minutes. Let cool in the dish on a wire rack.
In a small bowl, whisk the remaining 1 tsp. cinnamon and the confectioners' sugar and sift over the brownie. Using foil, lift the brownie from the pan. Cut into 16 rectangles.