Warm Mocha Tart

"Perfect shortbread made with melted butter...remarkable crust barely shrinks in the pan, so there is no need to weight or even prick it before baking. To ensure that the bottom remains crunchy, bake the crust fully, to a deep golden brown, before pouring in the filling." Excerpted from Seriously Bitter Sweet by Alice Medrich. Prep and cooking of the crust is included in the 'prep time'.

• Ready In: 57 mins
• Serves: 8

Ingredients

• For the Crust

• 7  tablespoons unsalted butter, melted
• 1⁄4 cup sugar
• 1⁄8 teaspoon salt
• 3⁄4 teaspoon pure vanilla extract
• 1  cup all-purpose flour (130 grams)

• For the Filling

• 3  tablespoons unsalted butter, cut into chunks (45 grams)
• 1⁄2 cup sugar (100 grams)
• 1⁄4 cup  premium  unsweetened cocoa powder (natural or Dutch-process, 25 grams)
• 1  cup heavy cream
• 1 1⁄4 teaspoons instant espresso powder or 1 1⁄2 teaspoons instant coffee powder
• 1⁄2 teaspoon pure vanilla extract
• 1  large egg, lightly beaten (room temperature)

Directions

1. Special Equipment Needed: 9 1/2-inch fluted tart pan with a removable bottom.
2. Position a rack in the lower third of the oven and preheat the oven to 350°F.
3. To make the tart crust: Mix the melted butter, sugar, salt and vanilla in a medium bowl. Add the flour and mix just until well blended. Don’t worry if the dough seems too soft. Press all of the dough very thinly and evenly into the bottom and up the sides of the tart pan.
4. Bake for 20 to 25 minutes, or until the crust is a deep golden brown.
5. Meanwhile, make the filling: Place the butter, sugar, cocoa powder and cream in a medium saucepan and cook over medium heat, stirring, until the mixture is blended and smooth and begins to bubble around the edges. Remove from the heat and stir or whisk in the espresso or coffee powder and vanilla.
6. Just before the crust is ready, whisk the egg thoroughly into the hot chocolate mixture.
7. Pour the filling into the hot crust and turn off the oven. Leave the tart in the oven until it quivers like tender Jell-O in the center when the pan is nudged, 10 to 12 minutes. Cool on a rack.
8. Serve the tart warm or at room temperature.
9. Chocolate Note: Either natural or Dutch-process cocoa works well here. The former has a livelier, more complex, fruity flavor, while the latter has a cozy old-fashioned flavor reminiscent of chocolate pudding.