Ginger gets horribly grumpy when people grind bits off of her. You have to be quick and sneaky, and sometimes a half teaspoon is as much as you can manage. (G)
A half teaspoon is what the original (culinary arts institute encyclopedic cookbook, circa 1950) recipe calls for. I tend to adjust based on the potency of the spices I am using. I regard quantities of spices as proportions, more or less. If I am stuck using the cheap junk from the dollar store, I might multiply the amount drasticly, if I am grinding fresh (my preferred) I almost have to alter the quanties, in this case less cinnamon and more ginger. A delicate spicing in this accentuates the apples without overwhelming them. You have to taste and make an educated guess. I think a bit more ginger in the cake is in order to balance the total quantity of cinnamon, however tastes vary. Depending on the apples and the mood of the house I sometimes add a dash of cloves, just a tiny bit. It seems to bring out the other spices without overdoing. It is a small cake, so you don't want to go too overboard.
NightMist