I'm planning a brew for a Christmas Spice/Winter Warmer. The base malt will be Maris Otter and specialties will be 60L English crystal. I want to make this beer have a multitude of flavors, but I want them all to be hints of the flavors. I want you to have to really search for the flavors. I'm going to hit it with hints of cloves, cinnamon, ginger, and nutmeg. I am going to rack onto a 1/2 to 1 pound of tart cherries (haven't decided which) in the secondary. Again, I'm just looking for a hint of cherry flavor. But the big question I have is how much vanilla extract. I want to add vanilla to define the spice flavor as unique compared to my pumpkin ale. Though I'm not using nearly the amount of spices in this beer as my pumpkin beer, but they are essentially the same spices. So, how much vanilla extract to give a hint of vanilla flavor in a 5 gallon batch?