For the Tart Shell
Combine in the bowl of an electric mixer until dough forms. Gently press into desired tart pan or individual tartlet pans. Place in freezer until firm. Place a small square of parchment paper on top of the dough and place either baking weights or dried beans on top. Bake in 350 degree oven until sides are slightly firm, approximately 10 minutes. Remove from the oven and let cool. Remove weights and bake again to crisp, approx. 5 minutes. If the dough is not baked enough it will be challenging to remove from pans

For the Caramel Mascarpone Ganache
Combine mascarpone and caramel sauce in the bowl of an electric mixer with a whisk attachment. Whip until stiff.

Spread in the bottom of the tart shell(s) and refrigerate.

Bring cream to a boil in a saucepan, pour over chopped chocolate in separate bowl. Starting from the middle stir until cream is incorporated.

For the Caramel Sauce
In a saucepan combine, in this order, water, sugar, and corn syrup. Bring to a boil and cook until syrup reaches desired golden color. While the sugar is boiling have a cup of water and brush near. Occasionally brush the sides of the pot with water to prevent the sugar from crystallizing. Once sugar syrup is golden carefully add the butter and heavy cream while stirring. Add liquid slowly to prevent splashing, the mixture will also bubble so make sure your arms are protected. Once all cream and butter is added remove from saucepan and place in desired storage container. Leave at room temperature stirring occasionally, once cool place in refrigerator to cool completely.

Assemble the Tart
Gently scoop chocolate cream mixture (ganache) onto the caramel mascarpone mixture already in tart shells. Make sure ganache is warm enough so that it forms a smooth top. Refrigerate the finished tart until ready to serve. Top with toasted, salted pistachios.