Chocolate-Dipped Pistachio Shortbread

From America's Test Kitchen

When made well, shortbread, with its moderately sweet, buttery flavor and distinctive sandy texture, is the perfect partner to a cup of tea or served alongside fruit for dessert, but often shortbread turns out bland and chalky. We wanted superlative shortbread with an alluring tawny brown crumb and pure, buttery richness.

In initial tests, we tinkered with various mixing methods and found that reverse creaming—mixing the flour and sugar before adding the butter, creating less aeration—yielded the most reliable results. To smooth out an objectionable granular texture, we swapped the white sugar for confectioners’ sugar. Still, our shortbread was unpleasantly tough. The problems were gluten and moisture. Gluten, the protein matrix that lends baked goods structure and chew, forms naturally when liquid and all-purpose flour are combined, even without kneading. The liquid in our recipe was coming from butter, which contains 20 percent water. To curb gluten development, we replaced some of our flour with powdered old-fashioned oats. We ground some oats to a powder and supplemented it with a modest amount of cornstarch (using all oat powder muted the buttery flavor). The cookies were now perfectly crisp and flavorful, with an appealing hint of oat flavor.

As for the moisture problem, we took a hint from recipes from historic cookbooks: we cooked the dough briefly, then shut off the heat and let it sit in the still-warm oven. The batch was dry through and through, with an even golden brown exterior. Crisp and buttery, our shortbread was anything but bland.