Chocolate Mint Tart

Preparation

1. Step 1

   Make the crust: In the bowl of a food processor, combine the flour, confectioners’ sugar, cocoa powder and salt. Pulse to combine. Add the butter and pulse until the mixture resembles coarse meal.

2. Step 2

   In a small bowl, whisk the egg yolk with 1 tablespoon cold water. Add the yolk mixture to the food processor and pulse until it is evenly distributed. The mixture will appear crumbly, but should hold together very easily when pressed. Add a bit more water, 1 teaspoon at a time, if necessary. Turn the mixture out onto a piece of plastic wrap and form it into a disc. Wrap the disc in plastic and refrigerate for at least 1 hour.

3. Step 3

   On a lightly floured surface, roll the chilled dough into a circle ¼- to ⅛-inch thick. Gently fit the dough into a 9-inch tart pan with a removable bottom and trim the top evenly. Repair any cracks or tears in the dough with the trimmings and reserve the trimmings, wrapped in plastic and kept at room temperature, to use later if necessary. Freeze for 30 minutes.

4. Step 4

   While the shell is chilling, heat oven to 375 degrees. Just before baking, dock the shell all over with a fork, and line the bottom and sides with aluminum foil. Bake the shell until it is cooked through and crisp, about 25 minutes. Remove the foil and, using the leftover dough, repair any cracks that may have formed. Cool the shell on a rack while you prepare the rest of the tart.

5. Step 5

   Make the white chocolate ganache: Heat the 1¾ cups heavy cream and mint leaves in a saucepan over medium-high until simmering. Turn off heat and let cream steep for at least 30 minutes and up to 1 hour.

6. Step 6

   Strain the cream through a fine mesh sieve, pressing on the leaves to extract as much cream as possible. Reserve 1 cup of the cream, covered, in the refrigerator.

7. Step 7

   Heat the remaining ¾ cup of cream until simmering and pour it over the white chocolate in a large bowl or the bowl of a stand mixer. Whisk the mixture until smooth, then let it cool to room temperature, about 30 minutes. If the chocolate is resisting melting, set the bowl over a pan of simmering water and whisk until smooth.

8. Step 8

   Add the butter and a pinch of salt and whip the ganache on high speed for 10 minutes. It will go from slightly translucent to opaque and aerated. Taste and add the peppermint extract if desired. Pour the whipped ganache into the cooled tart shell, smooth the top and refrigerate until firm, about 1 hour.

9. Step 9

   Make the bittersweet ganache: Bring the cream to a simmer in a small saucepan. Add the chocolate, butter and salt to a heat-safe bowl and whisk in the hot cream until smooth. If the chocolate is resisting melting, set the bowl over a pan of simmering water and whisk until smooth.

10. Step 10

    Use a spatula to spread the bittersweet ganache over the cooled white chocolate ganache. Refrigerate until firm, about 1 hour.

11. Step 11

    Just before serving, make the mint cream topping: Whip the reserved 1 cup of infused cream with the confectioners’ sugar to soft peaks. Add peppermint extract, if desired. Spread the whipped cream over the top of the ganache and serve the tart cold. Wipe off your knife in between slices for the cleanest cuts.