Donna Hay: Rhubarb and Dark Chocolate Tart

It's kinda late in the season for rhubarb, right?  I mean, it's a spring thing, isn't it?  Except I never saw any for sale this spring, because I was definitely going to try my hand at using it.  Big disappointment.  But then I walked into my local food mecca today, and there it was!  Big and beautiful and red as a ruby.  At this point, I'm not sure I care where they managed to find it, even if it involved a plane ride from South America.  Because look at this tart!  Rhubarb has now been added to the list of ingredients that have been done deliciously.

Rhubarb and Dark Chocolate Tart
Adapted from Donna Hay magazine, Issue 58, Aug/Sept 2011

Chocolate dough:
¼ cup cocoa powder
1¼ cups all-purpose flour
¾ cup powdered sugar
9 tablespoons cold unsalted butter, cut into small pieces
3 large egg yolks
2 tablespoons cold water (optional, depending on texture of dough)

Roasted rhubarb:
1 pound rhubarb, washed and trimmed, cut into 4-inch lengths
2 tablespoons granulated sugar
1 tablespoon rosewater

Dark chocolate ganache:
12 ounces bittersweet chocolate, chopped
1 cup heavy cream
Extra cocoa powder, for dusting

To make the chocolate dough:
Sift the cocoa powder, flour, and powdered sugar into a large bowl.  Add the cold butter and work it into the flour mixture by rubbing your palms together through the mixture until the mixture resembles fine breadcrumbs.  Make a well in the center and add the yolks. Work the yolks into the dough with a fork or even your fingers.  If the dough is slightly dry, add a spoonful or so of cold water until the desired texture is obtained.  Form the dough into a disk and wrap it in plastic wrap. Refrigerate until firm, or at least for 1 hour.

Roll out the disk of dough between two pieces of parchment until it is 3 mm thick.  Line a 9-inch removable bottomed tart pan with the dough and work it into the corners and edges. Trim and neaten it up.  Freeze the unbaked tart for half an hour or until very, very cold.

Preheat the oven to 350°F.

Dock the pastry with a fork.  Place the tart on a baking sheet and blind bake the tart for about 15 to 20 minutes until the pastry is fully cooked and appears dry (not glossy).  Remove the tart from the oven. If there are any bumps of air under the surface of the tart shell, press down very gently with a clothed hand (beware of steam) to release the steam. Let cool before unmolding it carefully and placing it on a plate.

To roast the rhubarb:
Toss rhubarb with the sugar and rosewater and bake it at 350°F on a parchment-lined baking sheet covered with foil, until the rhubarb is tender, about 20 minutes. Let cool completely before using.

To make the chocolate ganache:
Heat the cream in a small saucepan and when it is steamy, pour it over the chopped chocolate.  Wait a minute, then begin to stir it from the middle, out, until you obtain a smooth, silky ganache. Let the ganache thicken slightly before using.

To assemble the tart:
Line the bottom of the baked tart shell with the rhubarb.  Top with ganache, and let the tart set in the fridge for a couple of hours.  When you are ready to serve the tart, sprinkle the top with some cocoa powder.