Chocolate-Coconut Thumbprints

Whisk together all-purpose flour, whole-wheat flour, cocoa, baking powder, baking soda, and salt in a medium bowl. Set aside.

Beat butter and sugar together in a large bowl with an electric mixer on high speed until light and fluffy. Add egg and vanilla and beat until smooth. With the mixer on low speed, gradually add the flour mixture, mixing until just combined. Form the dough into a disk, about 1 inch thick, and wrap in plastic wrap. Refrigerate until firm, about 1 hour.

Meanwhile, position racks in upper and lower thirds of oven; preheat to 350°F. Line 2 rimmed baking sheets with parchment paper.

Roll the dough into 1-inch balls (about 2 tsp. each) and place on the prepared baking sheets. Make an indentation in each ball with your finger or the end of a wooden spoon. Bake until puffed and slightly firm to the touch, about 10 minutes. Let cool slightly and press the indentation again while the cookies are still soft to make a well for the chocolate. Let the cookies cool on a wire rack while you make the chocolate filling.

Heat cream in a small saucepan over medium heat until steaming (but not bubbling). Reduce heat to low and add chocolate; cook, stirring constantly, until melted. Remove from heat. Spoon a little of the chocolate mixture into the indentation on each cookie. (Depending on the size of the indentations, you may have some chocolate mixture remaining.) Top the chocolate filling with coconut. Let stand at room temperature until the chocolate sets, about 2 hours.