Fresh raspberries and mint leaves, for garnish (optional)
Preheat the oven to 350°. Butter two 1-cup ramekins and set them on a small baking sheet. In a small saucepan, melt the chocolate and butter over low heat, stirring occasionally. Let cool completely.
In a medium bowl, combine the egg, egg yolk and granulated sugar. Set the bowl over a pan of simmering water and beat at high speed until the mixture is thick and warm, about 4 minutes. Off the heat, continue beating the mixture until thick enough to form a slowly dissolving ribbon when a beater is lifted, about 2 minutes.