chocolate cake + orange buttercream = my favorite

Recipe adapted from Hannah's blog.Chocolate CakeFrom Southern Living2 (4-oz.) bittersweet chocolate baking bars, chopped1/2 cup butter, softened1 2/3 cups granulated sugar1/3 cup firmly packed light brown sugar3 large eggs2 cups all-purpose flour1 teaspoon baking soda1/2 teaspoon salt1 (8-oz.) container sour cream1 teaspoon vanilla extract1 cup boiling water.1. Preheat oven to 350°. Grease and