In this cake, the addition of Cognac or Grand Marnier adds a touch of flavor. Adding alcohol through liquor or liqueurs to baked goods can boost flavor and assist with the moisture level. It's important to consider your guests when cooking with alcohol - remember that although some of the alcohol does cook off during baking (about 65% in 30 mins bake time), a fairly substantial percentage (35%) is still present when it's time to eat.