Matcha Shortbread Cookies

A friend of mine was just admitted to the traditional French cooking program I attended four years ago (read all about it here and here), and the good news got me thinking about a type of cookie we learned to make in class as we approached the holidays, called sablés diamant.

These "diamond cookies" are classic butter cookies that you form using my favorite technique, referred to in English as slice-and-bake, in which you shape the dough into a log and slice it into simple rounds. I remember being surprised to see this method taught as part of the official culinary repertoire, because I've always thought of it as a home-style shortcut (as opposed to spreading the dough and cutting it into shapes with a cookie cutter), and not one that's particularly widespread in French households, either.

In any case, the true reason why it's used for these sablés diamant is not so much to save time as to make the diamond thing happen: the recipe has you roll the log in sugar before slicing, so that the edges of the finished cookies are prettily dotted with sugar crystals that sparkle like a hundred diamonds if you are blessed with a fervent imagination.

In addition to the visual appeal, this produces an ideal texture, the cookie tender and crumbly, its flanks offering a distinctly crunchy note. I decided to use the same idea to make matcha* shortbread cookies.

I used confectioner's sugar and ground almonds in the dough itself to make it extra smooth on the tongue, the better to highlight the contrast between center and rim. And I blended in a moderate dose of green tea powder: just enough to give the sablés a delicate grassy flavor without overpowering the round notes of butter and almond.

* Matcha is a fine powder made by grinding green tea leaves; it can be purchased from Japanse grocery stores, and from good tea shops.

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One last thing: I will be participating in a live Q&A session on the Times Online website this Wednesday, October 7 at 1pm GMT (London time). If your time zone and schedule allow it, please join in!

Update: The live Q&A session on the Times Online website is over, but you can still view the exchange.

Matcha Shortbread Cookies

- 100 grams (7 tablespoons) good-quality butter, softened (I use semi-salted butter; if you use unsalted, add 1/4 teaspoon sea salt)
- 50 grams (6 tablespoons) confectioner's sugar
- 1 egg yolk*
- 90 grams (3/4 cup) flour
- 40 grams (6 tablespoons) finely ground almonds (a.k.a. almond meal or poudre d'amande; look for it at natural food stores)
- 2 teaspoons matcha (green tea powder)
- 2 tablespoons sugar, preferably an unrefined cane sugar in coarse crystals, such as turbinado or demerara

Yields about 20 cookies.

In a medium mixing-bowl, cream together the butter and confectioner's sugar with a spatula. Add the egg yolk and mix it in thoroughly.

In another bowl, combine the flour, ground almonds, and matcha, and stir with a whisk to remove any lump. Add to the first bowl and stir it in until the mixture comes together to form a ball; don't overwork the dough. Roll it into a log with a circular or square** section, about 4-cm (1 1/2-inch) in width. Wrap in cling film and place in the freezer to firm up for 40 minutes (or in the fridge for 2 hours).

Preheat the oven to 180° C (360° F) and line a baking sheet with parchment paper. Sprinkle the sugar on a plate and roll the log in it to coat on all sides, pressing it down a bit into the sugar if necessary. Using a sharp knife, cut the log into 1-cm (2/5-inch) slices and arrange on the prepared baking sheet; the cookies will spread just a touch.

Slip into the oven and bake for 12 minutes, or until the cookies just begin to turn golden at the edges. Let rest for 5 minutes on the baking sheet before transferring to a rack to cool completely.

* You can freeze the unused egg white and save it until you have enough to make one of these recipes.

** To form a log with a square section, start by forming a regular log with a round section. Place it on a work surface, and press down on it with a small cutting-board to just flatten the top and bottom. Roll it by a quarter of a turn, and repeat to get two more flat sides.