Linzer Tart

I've been on a Pierre Hermé streak lately. I got his Chocolate Desserts from the library, and I've been flipping through it for inspiration whenever I wanted to bake something for a friend. Last time it was the chocolate pecan caramel Tart Grenbloise. This time, I wanted something more vibrant and brightly-flavored. I was thinking about a warm chocolate blueberry tart (yes, it's a good flavor combination) until I saw the photo of the linzer tart in the front insert. It was a photo of luscious chocolate ganache being spread onto a ruby red, seed-studded tart. I knew it was linzer tart, and I just had to make it.

When I envision linzer tart, I see the latticed-top version with raspberry jam peeking out behind the bars. This version, however, adds a rich chocolate ganache on top of crumbly, cinnamon-flavored crust and homemade raspberry jam. Since I'm still recovering from the super dense chocolate cream ganache in the Tart Grenbloise, I decided to make Pierre Hermé's chocolate milk ganache instead. The result was fantastic, a perfect balance between the acidity and brightness of raspberries and the deep chocolate ganache. The chocolate milk ganache had a pleasantly light texture, somewhere between truffle filling and chocolate mousse, and it matched well with the crumbly tart shell (well, whatever was left of the tart shell, anyway... more on that story below). I purposely kept the chocolate layer thin so it wouldn't bully the other flavors (or my palette), and it worked out very well.

The only thing I would change (other than the tart shell) was the raspberry jam. I had cut down the sugar by 15%, but I still found it too sweet. The boyfriend had the brilliant idea of adding spirits to the jam. I had great success with a vodka cranberry sauce last Thanksgiving, so a vodka raspberry jam could totally work. A splash of Grand Marnier probably wouldn't hurt, either...

* All recipes adopted from Chocolate Desserts

I. Raspberry Jam 
(This makes 1 1/2 cups of jam, twice as much as you'd need for the tart. But you can use it for so many things, including eating it with a spoon.)

1 pound (450 g) raspberries (I used frozen)
1 1/3 (270 g) cups sugar
1 tablespoon freshly squeezed lemon juice (I just squeezed in half a lemon)

Process the berries in a food processor for 5 minutes to release the pectin in the seeds (did you know that blending raspberries turns them a violent shade of magenta?).

Cook the raspberry puree with sugar in a heavy-bottomed pot until it comes to a boil, stirring occasionally. Cook for 10-15 minutes until the jam thickens slightly and the bubbles look clear. You'll be able to tell because the jam turns from magenta to deep red, and it becomes translucent. Take off the heat and stir in the lemon juice to taste. It can be kept in the refrigerator for about 1 month.

II. Bittersweet Chocolate Milk Ganache
(This makes 2 cups. If you like the ganache layer on the thin side, like me, you can fill two 9" tart shells.)

9 oz (260 g)  bittersweet chocolate, finely chopped.
1 cup (250 g) whole milk
1 stick plus 1 tablespoon (130 g) butter, at room temperature

Bring the milk to a full boil. While it is boiling, work the butter with a spatula until it is very soft and creamy. Pour the hot milk into a large bowl filled with the chopped chocolate. Stir the mixture with a rubber spatula in concentric circles, starting from the center and working outwards (I found the chocolate melted much more quickly in this case than in the standard cream-based ganache). Stir until the chocolate is melted and the mixture is smooth. Let it cool down for a minute or two before adding the butter.

Be careful not to let it cool too much, otherwise you won't be able to incorporate the butter. I didn't realize that the addition of butter cools down the ganache.  

Add the butter to the chocolate in three additions, stirring in concentric circle pattern. The ganache should be smooth and glossy when the butter is fully incorporated. Leave it at room temperature to set to a spreadable consistency, or chill it in the fridge for later use (it'll keep for up to 2 days, or up to 1 month in the freezer).

III. The Crust Who Shall Not Be Named

(Makes enough for one 9" tart.)

7 tablespoons (100 g) butter
2 1/2 tablespoons confectioner's sugar
2 1/2 tablespoons finely ground almond powder
1 hard-boiled egg yolk, processed through a fine strainer
1/4 teaspoon cinnamon
Pinch of salt
1 teaspoon dark rum
Pinch of double-acting baking powder
3/4 cup (105 g) all-purpose flour

Process the butter in a food processor until creamy (note: I have a 11 cup food processor and it was very difficult to process the butter because there's so little of it). Add the confectioners' sugar, almond powder, egg yolk, cinnamon, and salt; continue to process until smooth. Add rum and pulse to blend. Whisk the baking powder into the flour and add flour to the work bowl, pulsing until thoroughly blended. The dough will feel soft. Scrape the dough onto a piece of plastic wrap, shape it into a ball, then press it into a disk. Chill in the fridge for at least four hours.

Roll out the dough to a 1/4 inch thick circle and line your tart pan/ring with it. Pretty, isn't it?

Chill the dough for at least 30 minutes, then bake it blind (filled with rice, beans, or "pie weights") in a 350 F oven for 18-20 minutes. Remove the weights and bake for an another 3-5 minutes until honey brown. Cool to room temperature.

I had high hopes for this pastry crust. What I got in the oven, however, was this:

The pastry was so crumbly that the edges collapsed on itself!

A Science Moment: The hard boiled yolk was supposed to give the crust a "delicate crumbly texture". According to Cooks Illustrated, half of the weight of an egg yolk consists of water. The process of boiling solidifies the protein matrix in the egg yolk, which locks in that water. Less water in the dough equals a more crumbly crust, but in this case, I ended up with a pile of (albeit delicious) barely cohesive crumbs. Instead of the hard boiled egg yolk, I should have tried using a whole egg to add more binding power to the dough.

IV. Assembly

Spread 3/4 cup of the jam into the tart. You may need to heat up the jam first to make it spreadable.

 

Next, pour the ganache onto the crust. I like my ganache slightly warm so it will pour evenly into the tart and set up with a mirror-like finish.

Refrigerate for 30 minutes, or until the ganache is set. Pierre Hermé suggests serving this at room temperature, but I actually like the tart cold. It's easier to cut, and the coldness brings out the smoothness of the ganache.

Next time, I'll make this with a regular sweet tart crust instead.