Preheat oven to 325°F.
Mix flour, sugar, salt, and cardamom in a food processor. Pulse until mixed. Add butter and pulse until a crumbly dough begins to form. Add toasted piñons and pulse to incorporate.
Press the crumbly dough into an ungreased 9x9-inch pan. Poke all over with a fork.
Bake for 40–50 minutes, or until lightly browned.
Cool on a wire rack for about 10 minutes. Invert onto a cutting board. While still warm, remove pan and cut into desired shapes.