Egg and butter cream with chocolate

Ingredients:

• 450 g dark chocolate
• 340 g semi-sweet chocolate
• 3/4 cup egg whites at room temperature (4-5 medium eggs)
• 1.5 cups granulated sugar
• 1/4 tsp cream of tartar
• 3/4 tsp coarse salt
• 3 tsp vanilla extract
• 680 g of butter at room temperature
• 3 tsp instant espresso coffee (dissolve in 1.5 tsp water)
• 3 tbsp dark rum (or any flavoring of your choice)

Preparation:

1. Break the chocolate into pieces, place it in a heatproof bowl, and set it over a saucepan of simmering water. Stirring constantly, melt the chocolate in a double boiler until completely melted, then let it sit until it cools to room temperature.
2. In the bowl of an electric mixer, using the whisk attachment, combine the egg whites, sugar, and cream of tartar. Place the bowl over a pan of simmering water and heat the whites until warm to the touch, about 5 minutes. Return the bowl to the mixer and beat the whites on high speed for 5 minutes, or until the mixture cools and stiff peaks form.
3. Add the butter, one tablespoon at a time, beating on medium speed. Scrape the mixture down the sides of the bowl, then add the melted chocolate, vanilla extract, espresso, and rum (if using). Beat for 1 minute, until the chocolate is completely melted. If the cream seems soft, cool it and beat again. Yield: 4 tbsp.