INGREDIENTS
Butter (for the cake pan)
Flour (for the cake pan)
2 2/3 cups
all-purpose flour
1 tsp
baking powder
1 tsp
baking soda
1/2 tsp
salt
3 oz
bittersweet or semisweet chocolate, broken up
3 tbsp
unsweetened cocoa powder
1/4 cup
boiling water
1 cup
or 2 sticks) unsalted butter, softened at room temperature
1 cup
dark brown sugar
3/4 cup
granulated sugar
3
large eggs
2
egg yolks
1 tsp
vanilla extract
1 1/3 cups
sour cream
8 oz
semisweet chocolate, coarsely chopped
1 cup
sour cream, left at room temperature for 20 minutes
3/4 cup
powdered sugar, sifted into a bowl
1 tsp
vanilla extract
salt