Peppermint Chocolate Tart

To prepare crust: Preheat oven to 350 degrees F. Place water in freezer to cool while you make the dough.

Whisk all-purpose flour, whole-wheat flour, cinnamon, and salt in a medium bowl. Drizzle with oil and toss together with a fork until evenly damp and crumbly. Drizzle with the cold water; toss with the fork. Use your hands to bring the dough together into a ball, but don't knead or overwork it.

Place the dough between 2 large pieces of plastic wrap. Use a rolling pin to roll the dough into an 11-inch circle. Remove the top piece of plastic wrap and carefully invert the dough into a 9-inch tart pan with a removable bottom. Gently press the dough into the bottom and up the sides. Trim and patch where necessary. Prick the bottom of the crust all over with a fork.

Place the pan in the center of the oven. Bake until the dough pulls away slightly from the edges, about 20 minutes. Transfer to a wire rack and let cool completely.

Meanwhile, to prepare filling: Place chocolate chips in a heatproof medium bowl. Combine milk and cornstarch in a medium saucepan. Bring to a boil over medium-high heat; cook, whisking constantly, until the mixture looks thick like honey and frothy, about 5 minutes. Pour it over the chocolate chips. Add peppermint extract and salt; let stand for 1 minute without stirring. After 1 minute, stir gently with a spatula until all the chocolate is melted and the mixture is thick like pudding. Press a piece of plastic wrap directly on the surface. Set aside at room temperature for 20 minutes.

Pour the filling into the cooled crust. Gently swirl the surface of the chocolate with the back of a spoon, from one side to the other. Refrigerate, uncovered, for 4 hours.

If desired, crush peppermint candy and sprinkle over the tart. Use a hot knife to cut the tart into 12 pieces. Garnish each piece with 1 tablespoon whipped cream, if desired.