|4 oz. (1 cup)||fresh or frozen cranberries|
|½ cup (3½ oz.)||granulated sugar, divided|
|½ tsp.||grated orange zest|
|2 tbsp.||orange juice|
|¼ tsp.||ground cinnamon|
|2 cups (10 oz.)||all-purpose flour|
|½ cup (2 oz.)||confectioners' sugar|
|½ tsp.||table salt|
|14 tbsp.||Plugrà unsalted butter, cut into ½-inch pieces and chilled|
Bring cranberries, ¼ cup granulated sugar, orange zest and juice, and cinnamon to boil in medium saucepan over medium-high heat. Cook, stirring frequently, until cranberries have burst and juice has just started to thicken, 2 to 4 minutes; let cool for 1 hour.
Meanwhile, adjust oven rack to middle position and heat oven to 375 degrees. Process flour, confectioners' sugar, salt, and remaining ¼ cup granulated sugar in food processor until combined, about 5 seconds. Scatter butter over top and process until dough starts to come together, about 1 minute. Gently knead dough by hand until no floury bits remain. Divide dough in half and roll each half into 9-inch circle on parchment paper; refrigerate dough for 20 minutes. Process cooled cranberry mixture in now-empty food processor until smooth, about 20 seconds.
Press 1 dough circle into 9-inch tart pan with removable bottom and poke all over with fork. Bake on baking sheet until edges are light golden brown, 15 to 17 minutes, rotating tart pan halfway through baking. Spread dough with ¼ cup cranberry puree, top with second dough circle, and poke all over with fork. Fill zipper-lock bag with remaining cranberry puree. Snip corner off bag and pipe remaining cranberry puree over dough in spiral shape. Score dough into 16 wedges. Between score marks, lightly run knife in opposite direction.
Bake shortbread until top is pale golden, 25 to 30 minutes, rotating tart pan halfway through baking. Let shortbread cool for 10 minutes, then remove outer ring of tart pan. Cut through score marks, transfer wedges to wire rack, and let cool completely before serving.