INGREDIENTS
4 oz
unsweetened chocolate, chopped
1/4 cup
Dutch processed cocoa
1 1/4 cups
boiling water
3/4 cup
unbleached all-purpose flour
3/4 cup
cake flour
1 tsp
baking soda
1/4 tsp
salt
16 tbsp
(2 sticks, 227 grams) unsalted butter, softened but still cool
1 1/2 cups
packed (297 grams) dark brown sugar
3
large eggs, at room temperature
1/2 cup
sour cream
1 tsp
vanilla extract
2 cups
(4 sticks/ 454 grams) unsalted butter, at room temperature
2 cups
powdered sugar, sifted
1 1/2
teaspoons vanilla extract
8 oz
bittersweet chocolate, melted and cooled (I used Ghirardelli 60 percent)
2
(30-45 ml) tablespoons milk or heavy cream