| 1. | Adjust a rack one-third up from the bottom of the oven and preheat the oven to 325 degrees. Butter a 9-inch round layer-cake pan. Line the bottom with a round of parchment paper cut to fit. Butter the paper then dust all over with chocolate flour, shake out excess. Set aside. |
| 2. | Combine chocolate, butter, and sugar in microwave proof bowl and carefully melt these. Add eggs one at a time whisking after each addition. |
| 3. | Pour mixture into prepared pan cake pan. Place the pan on a jelly-roll pan and place in oven, then add a scant inch of hot water to the jelly-roll pan. |
| 4. | Bake for 1 hour and 15 minutes. Then, carefully remove pan from hot water and let stand until completely cool. |
| 5. | With a small sharp knife, carefully cut around the edge to loosen the sides of the cake from the pan. Cover pan with plate or board and turn over onto plate or board. Whack several times to loosen cake from pan. It will stick, be patient. |
| 6. | Refrigerate overnight. Peel off paper lining. Dust with cocoa powder. |