It was delicious, perfectly scrummy, and a subtle enough addition to not overpower the aroma of butter as they were baking. (I say "they" rather than "it" because I prefer to cut the shortbread into individual biscuits before baking.) When developing recipes, I always cut back on the sugar as much as possible. This barely sweet treat has less than 1/2 teaspoon sugar per biscuit (that's British English for "cookie").
(Makes 25 biscuits/cookies)
1/2 cup (4 ounces/113 grams) unsalted butter, room temperature
1/4 cup (1.75 ounces/50 grams) sugar
1 teaspoon vanilla extract
1/8 teaspoon salt
1/2 packed cup finely ground hazelnut meal
1 dip-and-sweep cup (5 ounces/142 grams) unbleached all-purpose flour
1 With electric mixer, cream butter well. Add sugar, vanilla extract and salt; continue creaming. Beat in hazelnut meal, then beat in flour. Scrape out onto piece of waxed paper or plastic wrap, shape into disk, wrap and chill for about 30 minutes.
2 Preheat oven to 350F/180C/Gas4. On very lightly floured surface, roll or pat dough into 1/4-inch-thick 7 1/2-inch square. Cut into 25 1 1/2-inch squares. Place on parchment-lined baking sheet. Bake for about 16 to 18 minutes; edges will be just barely starting to brown.