Over very low heat, heat the heavy cream until warm and add the chopped chocolate. Stir with a wooden spoon or silicone spatula until the chocolate has melted and remove from heat to cool to room temperature. Set aside.Combine the egg whites, sugar, and salt in a large clean metal, ceramic, or glass bowl. Set the bowl over a pot of steaming hot water on the stove. Be careful not to boil the water, it just needs to steam. Stir so not to cook the eggs on the side of the bowl. If you have a Kitchen Aid Mixmaster, use that mixing bowl. Once the egg whites have reached 150 degrees (145 degrees is safe, but why not error on the side of caution?) remove the bowl and using the whisk attachment (or a hand held beater) whip on medium high until the mixture has doubled in volume and turned white.Make sure the mixture has no trace of warmth at all before you start to add the butter one tablespoon at a time. If you don't let your meringue cool sufficiently before start adding the butter, you will have a big oily mess on your hands. Keep adding the butter little by little. Right before it comes together, it will look like it has completely separated and fallen apart. Don't worry, keep whipping and adding the butter.After it has all come together, add the vanilla bean scrapping or extract and cooled chocolate mixture. Keep scraping the side of the bowl to make sure it is all fully incorporated.This icing keeps beautifully in an air tight container in the refrigerator for up to 2 weeks and up to 3 months in the freezer.