Midnight chocolate mascarpone tart

makes one 9 inch tart (my tart pan with removable bottom measures 9” x 1½” deep)

For the tart shell:
8 oz. unsalted butter (2 sticks), room temperature
½ cup granulated sugar
2¼ cups all-purpose flour
½ teaspoon salt
2 teaspoons finely ground espresso (from espresso beans)

Lightly spritz the tart pan with nonstick cooking spray.
In the bowl of a standing mixer fitted with the paddle attachment, beat the butter on low speed and gradually add the sugar.  (Stop the mixer to scrape down the sides and the bottom of the bowl a few times.) When the butter/sugar mixture is smooth, gradually add the flour, salt and ground espresso. Mix on low speed until incorporated. The mixture will be crumbly, but will hold together when you pinch a bit of it between your fingers. Turn the dough out onto a sheet of parchment paper and gently gather it together into a cohesive piece of dough. For a 9 inch tart, you will use approximately 14 ounces of dough; the extra can be baked in mini tart pans or cut out as cookies or frozen for another time.
Dust the dough with a bit of flour (not too much) and then roll the dough into a circle approximately 11 inches in diameter and ⅛” thick. Transfer pastry to 9” tart pan with a removable bottom. (Dust your rolling pin with a little flour and roll the dough over the pin, gently peel away the parchment paper, then unroll the dough into the tart pan. Smooth the pastry across the bottom and evenly along the sides. Use a fork to “dock” (poke small holes) across the bottom of the tart to prevent it from puffing up in the oven. Set the tart pan on a baking sheet and chill until solid; about 15 minutes in the freezer and 30 minutes in the fridge. (The dough needs to be very cold before baking so the sides don’t slide down.) While the dough chills, preheat your oven to 350 degrees F.  When the tart shell is sufficiently chilled, bake (still on the baking sheet) on the middle rack of the oven for 25 minutes. The sides and bottom of the tart should be lightly golden and no longer raw to the touch. (Every oven is different so keep an eye on things. You may need a minute more or less.) Transfer the baking sheet with the tart pan to a cooling rack. Cool completely. (Can be made ahead one day before and left at room temperature; if so, when cool, cover with plastic wrap.) 
 
For the filling:
*Note: The filling is only as good as the quality of chocolate used.  I prefer bittersweet chocolate; Trader Joe's has a great assortment- I’m partial to their Pound Plus 72% Cacao Dark Chocolate Bar. Other favorites are Ghirardelli, Callebaut and Lindt. (Please don’t use semisweet chocolate chips- chips are meant to hold their shape in the oven and don’t melt the same way.)

12 ounces dark chocolate*, chopped (the finer it’s chopped, the smoother the result) 
8 ounces heavy cream
½ teaspoon instant espresso powder (I use Medaglia d’oro brand)
1 tablespoon liqueur of your choice; Frangelico, Amaretto or Kahlua
4 tablespoons unsalted butter, room temperature, cut into small pieces
 
Place the chocolate in a heatproof bowl. In a small saucepan, heat the cream until hot but not boiling; (the cream will bubble just around the edge). Remove from the heat and add the espresso powder. Stir gently to dissolve.  Pour the hot cream over the chocolate and let stand for 1 minute. Gently stir the chocolate until melted and smooth. Stir in your liqueur of choice. Let the mixture cool slightly at room temperature, about 15 minutes. Whisk the butter into the chocolate mixture, one piece at a time, just until blended. Stir gently to avoid air bubbles and a grainy texture. Pour the chocolate filling into the cooled tart shell. The chocolate will need to set up before you top it with the cream. You can let it sit at room temperature for several hours or refrigerate it if you need to expedite things.
 
For the mascarpone cream: (while you assemble your ingredients, chill your mixing bowl and whisk attachment)
 
zest from one small lemon (make sure to wash the lemon before zesting)
8 oz. (226 g) mascarpone
1¼ cups heavy cream
6 tablespoons powdered sugar, sifted (make sure to sift it to avoid lumps)
1 teaspoon vanilla extract
 
finely grated dark chocolate to garnish (optional)
 
Spoon the mascarpone into the bowl of your stand mixer. Add ½ cup of heavy cream to the bowl and use a rubber spatula to incorporate the cream with the mascarpone. Add the remaining heavy cream and the sifted sugar to the bowl. Place the whisk attachment on the mixer. With the mixer on low, beat the mascarpone/cream mixture just until soft peaks form. (It is dangerously easy to over whip mascarpone cream which will make it grainy.) Add the vanilla extract. Increase the speed to medium and whip until thick. It’s best to stop the machine and do the final few strokes by hand so you can control things. Fold in the lemon zest.  Cover and refrigerate until serving. 
Right before serving, add the mascarpone cream to the top of the tart. You can dollop it, use a small offset spatula, or pipe it using a pastry bag with a large star tip. If you wish, dust the top of the cream with finely grated dark chocolate. Cover and refrigerate any leftovers.
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