| 1. | Preheat oven to 350 degrees. Butter or oil an 8-inch square baking pan or heatproof glass dish. |
| 2. | Line pan with parchment paper, leaving a 1-inch overhang on 2 sides. Set aside. |
| 3. | Blend flour, salt, cinnamon, and acho chili powder in a small bowl. Set aside. |
| 4. | Melt chocolate and butter until smooth in a double boiler or bowl set on a saucepan of simmering water. Remove bowl from heat and allow to cool until room temperature. |
| 5. | Stir sugar into cooled chocolate mixture until combined. Whisk eggs into mixture, one at a time, whisking until smooth after each addition. Whisk in vanilla. Gently fold in flour blended dry ingredients. |
| 6. | Pour batter into prepared pan, smoothing out with a spatula. Bake 40 to 45 minutes (until a toothpick inserted in center comes out with only a few moist crumbs attached). Transfer pan to a wire rack to cool completely. |
| 7. | Run a knife or spatula around the edges of the pan. Using the parchment edges, lift brownies out of pan and onto the rack. Transfer to a cutting board; cut into 16 or 25 squares, depending on preference. |