INGREDIENTS
1 1/2 cups
granulated sugar
1/2 cup
packed light-brown sugar
3/4 cup
unsweetened cocoa powder
1 tsp
baking soda
3/4 tsp
salt
1 cup
boiling water
3/4 cup
canola oil
2
large eggs
3
large egg yolks
1 tbsp
vanilla extract
2 cups
all-purpose flour
1/3 cup
milk
1/3 cup
sour cream
1 1/2 cups
butter (, at room temperature (I like to use 1 cup unsalted and 1/2 cup salted))
3 3/4 cups
+ 2 Tbsp powdered sugar
1/2 cup
+ 2 Tbsp cocoa powder
3 tbsp
heavy cream
1 tsp
vanilla extract