Melty Chocolate-Truffle Cookies

Directions

1. 1.

   Preheat oven to 375° with racks in center and upper third. Line 2 baking sheets with parchment.

2. 2.

   Whisk together flour, sugar, cocoa powder, baking powder, salt, and espresso powder (if using). Rub butter into dry ingredients until mixture resembles breadcrumbs. Stir in chocolate.

3. 3.

   Whisk together egg and vanilla. Add egg mixture to chocolate mixture; stir with a fork until mixture is slightly moistened. Form dough into a ball; wrap in plastic; refrigerate 30 minutes.

4. 4.

   Shape dough into tablespoon-size balls. Roll each in powdered sugar to coat; place on sheets 2" apart. Bake until just set but still slightly undercooked, about 10 minutes. Let cool on sheets 5 minutes; transfer to wire racks to cool completely. Serve warm.