I received a coupon book from Lactantia in the mail, and this was one of the recipes printed in the book. I made this recipe with some heavy changes, but decided to post the recipe in its original form here.
Preheat oven to 375°F Butter a 10-inch springform pan and line with a round of parchment paper.
Melt bittersweet chocolate with 2 oz milk chocolate and the butter in a large, heavy saucepan set over low heat until smooth. Remove from heat; whisk in sugar and salt, followed by eggs and vanilla. Sift cocoa powder over chocolate mixture, stir until combined.
Scrape batter into prepared pan. Bake for 25-30 minutes or until top has a thin crust and the edges pull away from pan. Cool on a rack for 10 minutes. Carefully invert onto a serving plate and remove parchment paper. Cool completely.
Meanwhile, heat 1/4 cup whipping cream in a small saucepan set over low heat. Add remaining milk chocolate; cook, stirring until melted and smooth. Cool to room temperature.
Beat remaining whipping cream until very stiff. Gently fold chocolate mixture into whipped cream until uniformly combined. Chill for at least 30 minutes.
Mound chocolate cream onto centre of cake just before serving. Garnish with chocolate curls or dusting of cocoa powder.