2 cups all-purpose flour
1 1/2 tsp salt
1 cup butter softened
3/4 cup confectioners sugar
3 Tbs Crio Bru grounds
Preheat oven to 300* with rack in the upper third. Whisk to combine flour and salt in a bowl. In separate bowl beat butter with an electric mixer on medium-high speed until fluffy about 3 minutes, scraping down side of the bowl as necessary.
Gradually add confectioners sugar; beat until pale and fluffy, about 2 minutes. Reduce speed to low and add flour mixture all at once just until combined, and add crio bru grounds.
Divide dough into 2 disks, press each into a buttered 6-inch springform or cake pan. Using a wooden skewer, pierce dough all over at 1/4 inch intervals, Score each into 8 wedges, bake 45-55 minutes.
Transfer pans to a wire rack, re-cut shortbread along the score, let cool completely.
Drizzle melted chocolate over cut shortbread if desired.