Chocolate Crostata with Mascarpone Mousse

makes one 9½-inch tart, about 10 servings

Note:  For the crust, I used regular salted butter and omitted the salt. 

Equipment needed:  9½" tart pan and a piping bag with medium to large tip

For the chocolate crust:
7 Tablespoon unsalted butter, at room temperature
5/8 cup sifted confectioners' sugar (odd amount, I know - so just measure a ½ cup and add another ⅛ cup)
1 large egg yolk
1 cup unbleached all-purpose flour, plus extra for rolling
4½ Tablespoons cocoa powder (I used less - about 3 Tablespoons)
¼ teaspoon kosher salt

For the chocolate filling:
2 Tablespoons cold water
1 envelope (2¼ teaspoons) powdered gelatin
1 cup heavy cream
¾ cup whole milk
4 Tablespoon plus 1½ teaspoons granulated sugar
¼ teaspoon kosher salt
6 ounces chopped bittersweet chocolate
2 Tablespoons coffee liqueur, such as Kahlua (optional)
¼ teaspoons vanilla extract

For the Mascarpone Mousse:
(makes 3 cups)
8 ounces mascarpone cheese
¾ cup heavy cream
2 Tablespoons granulated sugar

Make the Chocolate Crust:
Place the butter and confectioner's sugar in the bowl of a stand mixer fitted with the paddle attachment. Cream together, on medium speed, until thoroughly combined and light and creamy, about 2 minutes. Add the egg yolk and continue to beat until combined, scraping down the sides of the bowl. Next add the flour, cocoa powder, and salt. Mix on low speed until the dry ingredients and just absorbed to form a dough. Do not overmix. Turn out onto a clean surface and form into a disc.  Wrap the dough in floured plastic wrap and chill for 1-2 hours.

Preheat the oven to 350°F and insert 2 racks. Line a sheet tray with parchment paper.

Dust a work surface and rolling pin with flour and roll out the dough until it is ⅛ inch thick. Roll the dough loosely around the floured rolling pin, then unroll it onto the tart pan.  Gently ease the dough into the bottom and sides of the pan.  If there are any holes in the tart shell, patch them with pieces of dough torn from the rough edges.  (Note:  when I made this, I really couldn't get a whole nice round dough rolled out, like I can with pie dough.  This can be pretty common with tart dough. If you're having trouble, don't worry about rolling out a perfect round of dough - just press the dough into the pan and up the sides. It's fine). Trim off any remaining excess dough by running the rolling pin over the edges of the pan. Place these dough trimmings on the parchment-lined sheet tray.

Next line the tart shell with a generous piece of parchment and fill with pie weights or dried beans. Place the sheet tray with the dough scraps on the lower rack in the oven and the tart shell on the upper rack.

Bake the dough scraps for 12 minutes; remove from the oven and let cool.  Bake the tart shell for another 15 minutes.  Remove the parchment paper and pie weights from the shell, then return the tart shell to the oven and continue baking for an additional 15 minutes, or until the bottom is firm and dry to the touch. Leave to cool on a rack until room temperature, about 40 minutes to 1 hour.

Break off a small piece of a cooled scrap - it should break easily. If the dough seems too soft, return the scraps to the oven for another 3-5 minutes. Once the scraps are cooked sufficiently, break them by hand into crumbs of roughly varied sizes. Transfer to an airtight container and store at room temperature until ready to serve the tart.

Make the Chocolate Filling:
Place the cold water in a very small bowl. Sprinkle the gelatin onto the water. If there are any undissolved clumps of gelatin, use a fork or tiny whisk to break them up. Let the soaking gelatin sit at room temperature while preparing the rest of the ingredients for the filling. 

Place the heavy cream, milk, sugar, and salt in a small saucepan. Bring to a simmer over medium heat. Reduce the heat to low, then add the soaked (or "bloomed") gelatin to the dairy mixture and whisk to combine. Next add the chocolate to the pan and whisk until completely melted and incorporated. Remove the chocolate mixture from the heat and whisk in the coffee liqueur and vanilla extract. Pour the filling into the cooled tart shell.

Chill uncovered in the refrigerator for several hours or overnight until the filling has set completely.

Make the Mascarpone Mousse:
Using a stand mixer with a wire whisk attachment or a handheld electric mixer, combine the mascarpone, heavy cream and sugar and beat on medium speed until the mixture holds medium to stiff peaks, about 2 minutes. Be careful not to over-whip the mixture or it will quickly turn to butter. Use immediately; or you can store it in an airtight container, refrigerated, for up to 1 day.  (Mine was fine for 3 days in the fridge.)

To serve, place a slice of the chilled tart on a plate, pipe a generous amount of the mascarpone mousse on top and sprinkle with the tart shell crumbs. 

The recipe comes from Katherine Thompson of L'Apicio NYC

The Italian Dish