INGREDIENTS
2 cups
(14 ounces/400 grams) sugar
1 3/4 cups
(7.5 ounces/220 grams) all-purpose flour
1 cup
(4 ounces/120 grams) dark or dutch-processed cocoa powder (I used 3/4 cup Dutch processed and 1/4 cup black cocoa for color – do not use all black cocoa).
2 tsp
baking soda
1 tsp
baking powder
1 tsp
kosher salt
2
large eggs, at room temperature
1 cup
buttermilk
1 cup
boiling water
3/4 cup
vegetable oil or light olive oil
1 tbsp
vanilla extract
2 cups
unsalted butter, softened
2 1/2 cups
powdered sugar, sifted
1 1/4 cups
dark or Dutch processed cocoa powder (I used 1/4 cup black cocoa and Dutch-processed for the rest), sifted
1/2 cup
full fat sour cream, at room temperature
1/2 cup
hot water
2 tsp
vanilla extract
fine sea salt
10 oz
dark chocolate (60-70%), melted and cooled to lukewarm