1 Cup (2 sticks) unsalted butter, softened to room temperature
1/2 Cup powdered sugar
1 tsp freshly-Ground Black Pepper
3/4 tsp Kosher Salt
2 Cups all-purpose flour (plus a little more)
1 Cup finely-grated Parmesan (about 2 oz)
1 Tbsp Fennel Seeds
1 tsp Fleur de Sel or Coarse Sea Salt
2 Tbsp Extra-Virgin Olive Oil
Use an electric mixer, on low speed, with the beater or paddle attachment to beat the softened butter until smooth, 1-2 min. Add powdered sugar, pepper, and kosher salt while continuing to beat. Increase speed to medium and beat, occasionally stopping to scrape down the sides of the bowl with a spatula, until the mixture is light and fluffy, about 5 min. Reduce mixer speed to low before adding the flour and cheese, a little bit at a time, just until ingredients are incorporated.
Using your spatula, scrape the dough together into a ball, then wrap the dough-ball in plastic, before flattening the wrapped dough into a rectangle. Allow dough to chill in the refrigerator until firm, at least 2 hours. [Dough can be made up to 5 days ahead, but keep it chilled, removing from refrigerator and allowing dough to come to room temperature for 30 min completing the following steps.]
Preheat oven to 350°F, and put the baking rack in the middle of the oven. Pour the fennel seeds in a resealable plastic bag, and coarsely crush them with a rolling pin or other heavy object. [Or, use a spice mill or clean coffee grinder until fennel is coarsely crushed.] Transfer crushed fennel to a small bowl, and add the sea salt. Set fennel salt aside.
Line a rimmed baking sheet with parchment paper and remove plastic wrap from rectangular dough. Use the rolling pin on a lightly-floured surface to roll the dough into a 10″ x 8″ rectangle that is about 1/4″ thick. With a sharp knife, cut dough rectangle into thirds crosswise, and rotate the dough 90 degrees to cut those thirds into six pieces.
Arrange sliced cookies on the parchment-lined baking sheet, leaving about 1″ between pieces. Brush tops of cookies liberally with olive oil, then sprinkle with the fennel-sea salt blend.
Bake for 20 – 25 min, being sure to rotate cookie sheet after about 10 in. When cookies turn golden brown with slightly browner cheesy bits, they are done. Allow shortbreads to cool the baking sheets for at least 10 minutes before removing to a cooling rack.
Can be served while still warm, or later, at room temperature.
DO AHEAD: Shortbread can be made up to 2 days ahead. Store completely cooled cookies in an airtight container at room temperature for up to one week.
Adapted from Epicurious