Preheat oven to 350°F Make tassie pastry (#59854) and line mini muffin cups with this pastry.
Melt chips and butter in saucepan over low heat.
Remove from heat.
Stir in sugar, egg, and vanilla.
Place a whole hazelnut in center of each pastry-lined cup.
Top with 1 rounded tsp of chocolate mixture.
Bake for 20-25 minutes.
Immediately, and very carefully using the tip of a pointed knife, gently knudge out each tassie out of its cup and transfer to a rack to cool.
If they cool in the pan too long, they are more difficult to remove.
Your first couple may break (those are the ones I eat on the spot- the rewards of making them!), but you will soon learn just the right'move' to remove them perfectly.