The first time I tasted Sienese almond cookies was in Tuscany, in fact not too far from Siena. My husband Marc and I were vacationing at Borgo Pretale, an enchanting hotel tucked away in luscious green hills, surrounded by lavender, vineyards and sunflower fields — the quintessential Tuscan destination!
Note: I purchase the almond meal/flour from Bob's Red Mill. However, you can make your own by finely grounding the almonds in a food processor. Use blanched almonds and a little bit of flour (1 tablespoon of flour for every cup of almonds: This will prevent the almonds from turning into almond butter!). Process until very finely ground. It is hard to get the almonds as finely ground as the commercial almond meal/flour but it will still be adequate for the recipe. If grinding your own almonds, omit the 2 tablespoons of flour called for in the recipe.
Preheat the oven to 425 degrees.
Place the almond meal, flour, ¾ cup of the sugar, baking powder, and salt in a medium-sized bowl. Stir until well blended. Place the egg whites and almond extract in the bowl of an electric mixer. Whip at high speed until firm peaks form.
Add the whipped egg whites to the almond mixture and stir with a silicone spatula until the dough just comes together. Do not overmix or the cookies will be heavy. The dough will be soft and a bit sticky.
Sprinkle the remaining powdered sugar on a work surface and on your fingers. Using a teaspoon, grab a bit of the dough (about the size of a large olive). Drop the small mound of dough in the powdered sugar and roll it around until well covered with the powdered sugar. Shape into a 2-by-½-inch lozenge and gently flatten the top with the tips of your fingers.
Place on a baking sheet lined with parchment paper or a Silpat. Repeat until you have shaped 24 lozenges. Bake until the cookies have risen and are pale golden, about 10-12 minutes. Remove from the oven and let cool for 2 or 3 minutes. Transfer to a cooling rack and let cool until room temperature. Store in an airtight container for up to 2 weeks.