3 Layer Guinness-Chocolate Cake Ingredients 2 cups stout (such as Guinness) 2 cups (4 sticks) unsalted butter 1 1/2 cups unsweetened cocoa powder 4 cups all purpose flour 4 cups sugar 1 tablespoon baking soda 1 1/2 teaspoons salt 4 large eggs 1 1/3 cups sour cream for the icing: 2 cups whipping cream