In a microwave safe bowl, combine the chopped chocolate and the butter. Heat in the microwave until melted, about 35 seconds depending on your microwave, and stir to melt completely. Whisk in the egg yolks and set aside to cool.
Pour the cream into a chilled bowl of a mixer and beat on medium speed until it starts to thicken. Add the sugar and vanilla and whisk until the cream starts to form stiff peaks. Carefully fold the whipped cream into the cooled chocolate mixture. Serve immediately or cover and chill until ready to serve.
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.