This simple six-ingredient chocolate shortbread was originally published in the King Arthur Flour Cookie Companion cookbook. Rich and chocolate-y, it comforts and soothes the palate with its buttery goodness. The possibility of endless variations (see "tips," below for inspiration!) will keep you baking these cookies over and over and over.
Preheat the oven to 300°F. For thin, crisp chocolate shortbread, grease two 8" square pans. For thicker shortbread, grease one 9" square pan.
To avoid over-creaming, we recommend that you stir the dough by hand. In a medium-sized bowl, stir together the butter, salt, and sugar until well blended.
Add the cocoa, vanilla, baking powder, and flour, and mix until you have a smooth, slightly stiff batter.
Press the dough into your prepared pan(s) and prick all over with a fork. This will keep the shortbread from developing bubbles under the crust.
Bake the shortbread in two pans for 35 to 40 minutes; the single 9" pan will take about 50 minutes. Remove from the oven and cool for 5 minutes.
Invert the pan(s) over a clean sheet of parchment and turn out the shortbread. While still warm, cut each square into 12 pieces. Cool completely before serving.
Store chocolate shortbread, well wrapped, for up to a week; freeze for longer storage. The flavor improves as the shortbread ages.
Chocolate-Chocolate Chip-Walnut Shortbread: Prepare as directed, stirring in 1/4 cup mini chocolate chips and 1/4 cup diced walnut pieces before baking.
Chocolate-Orange-Spice Shortbread: Prepare as directed, stirring in 1/2 cup candied diced orange peel, 3 drops orange oil, 1/4 teaspoon allspice, 1/4 teaspoon ginger, and a pinch of cloves. Bake as directed. This version was a winner in our test kitchen tastings — a real home run.
