With Tonka Beans, 'less is more' as the taste/fragrance is so strong you only need a very small amount; just the gratings of approximately 1/8-1/4 of a bean.
They are actually a member of the pea family, Dipteryx Oderata, but the seed is actually more of a bean shape.
The fragrance and taste work in combination together, providing strong vanilla, cherry, cinnamon, caramel and honey. Smokey notes can also come through.
Use the gratings of a Tonka bean much the same as nutmeg into the base for ice cream, pannacotta, custards, crème brulee etc.
They can also be combined with cocoa and chocolate in chocolate cakes and biscuits and of course desserts.
Like vanilla, Tonka Beans can also be used in savoury cooking, such as fish dishes.
Licorice, nutmeg, cassia(cinnamomum cassia) and Tonka bean all contain a compound called Coumarin, which in large amounts can be toxic.
But to quote www.theatlantic.com/health journal 'Humans would need to eat an unreasonably bovine amount of tonka bean to fall ill. The shavings of a single bean is enough for 80 plates. At least 30 entire tonka beans (250 servings, or 1 gram of coumarin total) would need to be eaten to approach levels reported as toxic—about the same volume at which nutmeg and other everyday spices are toxic'.
So, just use a small amount, and delight the pallet of your guests in your mystical delicacy, and remember;
“Less is More”