Chocolate Ganache: 8oz dark chocolate (chopped or chips), 1/2 cup heavy cream, 1/4 teaspoon kosher salt, 1 teaspoon vanilla extract. Place all ingredients in a double boiler, or a bowl on top of a pot of boiling water, making sure the bowl doesn't touch the water. The idea is to heat and melt the ingredients, not to cook them. Stir until incorporated. You can learn more about ganache and watch a video on The Joy of Baking.
Whipped Cream: Whisk 1 cup heavy cream with 1/4 cup confectioners sugar, until it reaches a soft peak. You can use less or more sugar depending on how sweet you like it.
Each element can be made ahead and quickly assembled when you're ready, so this is a great option for a dinner party. The ganache will harden slightly at room temp and can be reheated to serve.