Melt the chocolate in a medium bowl set over (but not in) a saucepan of simmering water, stirring often, until smooth. Remove from heat and let cool slightly.

In a small saucepan, whisk together the egg yolks, espresso powder, 4 tablespoons of the sugar, and ¾ cup of the cream. Cook over medium heat, stirring constantly with a rubber spatula, until the mixture lightly coats the back of the spatula, 2 to 3 minutes (do not boil). Strain into the melted chocolate and whisk until smooth. Refrigerate until completely cooled, about 30 minutes.

Using an electric mixer, beat the remaining 1 ¼ cups cream and 2 tablespoons sugar until stiff peaks form.

In 3 additions, fold the whipped cream into the chocolate mixture. Divide among 8 serving glasses and refrigerate for at least 30 minutes (if longer, bring to room temperature before serving). Sprinkle with the shaved chocolate before serving.