Directions

1. Heat oven to 350 degrees. Stand cones on an ungreased baking sheet. In a mixing bowl, whisk together flour, baking soda, and salt; set dry ingredients aside.
2. Fill a medium saucepan with water and set over medium heat; bring water to a boil. Reduce heat, and let water simmer. In the metal bowl of an electric mixer, combine milk, 2 1/2 ounces chocolate, and 1 stick butter. Set bowl over simmering water, stirring occasionally, until butter and chocolate have melted. Remove bowl from heat; stir in 1 cup sugar.
3. Transfer bowl to mixer fitted with the paddle attachment. Add reserved dry ingredients, and beat until well combined. Add egg and 1 teaspoon vanilla; beat to combine. Pour batter into cones, filling each cone three-quarters full.
4. Transfer baking sheet to oven, and bake until domes form and a cake tester inserted into the center of a cupcake comes out clean, 20 to 25 minutes. Remove from oven, and transfer to a wire rack to cool completely.
5. Meanwhile, make the icing: Combine remaining 1/2 cup plus 2 tablespoons sugar and cream in a heavy saucepan. Set over high heat, and bring to a boil, stirring constantly. Reduce heat to medium; simmer, without stirring, 5 minutes. Remove pan from heat; add remaining 2 1/2 ounces chocolate, stirring until melted. Stir in remaining 4 tablespoons butter and 1/2 teaspoon vanilla. Chill, stirring occasionally, until icing is cool enough to spread. Using an offset spatula, spread icing over cupcake tops. Serve.