Ingredients
Cupcakes
5 oz. semisweet chocolate, coarsely chopped
2 cups cake flour
1/2 teaspoon salt
1/2 cup sour cream
5 tablespoons cocoa powder
2 1/2 teaspoons baking soda
4 eggs, at room temperature
2 teaspoons vanilla extract
1 1/2 cups hot coffee
12 tablespoons (1 1/2 sticks) unsalted butter, at room temperature
1 1/4 cup plus 2 tablespoons brown sugar
Frosting
6 oz. white chocolate, finely chopped
1 1/2 cups cold heavy cream
Preparation
To make the cupcakes: Preheat oven to 350 F. Line two cupcake pans with paper liners.
Place the chopped chocolate in a heatproof bowl and microwave until melted. Set aside to cool slightly. In a medium bowl, whisk the flour and salt together. In another medium bowl, whisk together the sour cream, cocoa powder and baking soda, then slowly whisk in the hot coffee until the mixture is smooth.
In the bowl of a stand mixer, cream the butter and brown sugar on medium speed until light and fluffy, about 3-4 minutes. Add the eggs, one at a time, beating well after each addition, then add the vanilla extract. Add the melted chocolate and beat to incorporate. With the mixer on low speed, add the flour mixture alternately with the liquid mixture (beginning and ending with the flour mixture), beating just until all ingredients are incorporated.
Divide the batter evenly among the cupcake liners. Bake for 18-20 minutes.
To make the white chocolate whipped cream: Place the chopped white chocolate in a heatproof bowl and set the bowl over a pan of simmering water. Melt, stirring occasionally. Meanwhile, bring 1/2 cup of the cream to a boil in a small saucepan. When the chocolate is fully melted, move the bowl to a work surface and pour in the hot cream. Let stand for 1 minute. Stir gently until the cream is incorporated and the mixture is smooth. Let the chocolate/cream mixture stand until it is completely cool.
In the bowl of a stand mixer fitted with the whisk attachment, beat the remaining 1 cup of heavy cream only until it holds the softest peaks. With the mixer on high speed, add the white chocolate all at once and continue to beat just until the mixture holds firm peaks. Transfer the cream to a bowl, press a piece of plastic wrap gently against the surface and refrigerate for at least 2 hours.
