This classic marble cake recipe is a perfect combination of vanilla and chocolate flavors. The cake is moist, tender, and has a beautiful swirl pattern. To make this cake, you will need all-purpose flour, baking powder, salt, unsalted butter, granulated sugar, eggs, vanilla extract, milk, and cocoa powder. The cake batter is divided into two parts, and one part is mixed with cocoa powder to create the chocolate batter. The two batters are then swirled together to create the marble effect. This cake is perfect for any occasion and is sure to impress your guests.