Ingredients

3/4 c. unsweetened Dutch-process cocoa powder

3 tbsp. unsweetened Dutch-process cocoa powder

1/2 c. boiling water

2 tbsp. boiling water

3 3/4 c. cake flour (not self-rising)

1 1/4 tsp. baking soda

3/4 tsp. Coarse salt

15 oz. unsalted butter

2 3/4 c. sugar

1 tbsp. sugar

1 tbsp. pure vanilla extract

1 tsp. pure vanilla extract

5 large eggs

1 1/4 c. whole milk

Preparation

Step 1Mix cocoa powder and boiling water in a bowl until smooth. Let cool.Step 2Sift flour, baking soda, and salt into a large bowl. Beat butter and sugar with a mixer on medium speed until pale and fluffy, 3 to 4 minutes. Beat in vanilla. Add eggs, 1 at a time, beating well after each addition and scraping bowl as needed.Step 3Pour milk into cocoa mixture in a slow, steady stream, whisking until smooth. With mixer on low speed, add flour mixture to butter mixture in 3 additions, alternating with cocoa-milk mixture, starting and ending with flour mixture. Use immediately.