Steps
1. Preheat the oven to 350°F. Grease a small oven-proof dish with the butter.
2. In a medium saucepan, whisk together the flour and milk. Heat over medium heat, whisking constantly, until the mixture thickens.
3. Remove from heat, and stir in the cocoa powder and sugar. Add the egg yolks and stir until combined.
4. In a separate bowl, beat the egg whites until stiff peaks form. Gently fold the egg whites into the chocolate mixture.
5. Pour the mixture into the prepared dish, and bake for 25 minutes, or until the top is golden brown.
6. Serve warm with a dollop of whipped cream.