Chocolate Fudge Cake

Ingredients

• 2 ¼ cups (295 g) cake and pastry flour
• 1 cup (120 g) Dutch process cocoa powder
• 1 cup (200 g) granulated sugar
• 1 ½ tsp (4.5 g) baking powder
• 1 tsp (5 g) baking soda
• ½ tsp (2.5 g) salt
• 1 cup (200 g) packed light brown sugar
• 1 ½ cups (375 mL) buttermilk
• ½ cup (125 mL) vegetable oil
• ¼ cup (60 mL) strong coffee
• 4 large eggs
• 1 tsp (5 mL) vanilla extract
• ¾ cup (175 g) unsalted butter, cut into pieces
• 4 ounce (120 g) bittersweet chocolate, chopped
• ½ cup (60 g) cocoa powder, sifted
• 1 cup (250 mL) full-fat sour cream
• 3 cups (390 g) icing sugar, sifted