unsweetened cocoa powder
- Preheat oven to 300ºF (150ºC). Lightly grease an 8-inch pie plate.
- Sift together the flour, cocoa powder, and salt; set aside. Stir the eggs into the sugar until smooth. Add the flour mixture, and stir until combines. Pour in the vanilla extract and butter; stir until well combined. Pour into prepared pie plate.
- Bake on the lower rack of the preheated oven for 35 minutes, or until the center has slightly set. Allow cake to cool for 1 hour in the pie plate. Serve warm, or refrigerate overnight and serve cold.