Caramel Chocolate Truffle Tarts

Wonderful rich chocolate tarts.  A nice desert to share with friends.

Truffle Tarts
1 box 255 g tart shells
1/3 cup whipping cream
1/3 cup each dark and milk chocolate chips
1 tbsp salted butter

Caramel:
1/2 cup granulated sugar
1/4 cup water
1/4 cup whipping cream
1 tbsp butter
1 tsp vanilla extract

1. Truffle Tarts:  Preheat oven to 375F.  Arrange tart shells on a baking sheet.  Dock bottoms with a fork, then bake for 10 to 12 minutes.  Cool completely.
2. Heat whipping cream in a microwave safe bowl for 1 minute or until steaming.  Add chocolate and butter, stirring until smooth.   Pour warm filling into cooled tart shells.  Chill until set.
3. Caramel: Meanwhile, mound granulated sugar in the centre of a medium, heavy saucepan set over medium heat.  Add water; cover and bring to a boil without stirring (about 4 minutes).  Uncover and cook, swirling the pan often, until the sugar turns a deep amber colour.
4. Remove from heat.  Immediately, wearing oven mitts, slowly whisk in whipping cream until smooth; stir in butter and vanilla.  Let cool for 20 minutes.  Spoon evenly over chocolate.  Chill until set (about 2 hours.).