Preheat the oven to 350°F. Line an 8-inch square baking pan with parchment paper, letting the ends extend up the sides (this will make it easier to lift the bars out later). In a bowl, combine the flour, butter and confectioners' sugar.
Pat the combined ingredients into the prepared pan. Bake the crust until it's golden brown, 18 to 20 minutes.
Meanhwhile, to make the cranberry curd, add the cranberries, sugar and orange juice to a large saucepan. Cook them over medium heat until the cranberries burst, about 8 to 10 minutes, stirring occasionally. Let the mixture slightly cool. Transfer it to a blender and puree until smooth. Send the mixture through a fine mesh sieve, and discard the solids. Stir in the orange zest, butter and egg yolks until the curd mixture is smooth.
Pour the cranberry curd evenly over the crust. Bake the bars until the curd is set and top appears dull, 15 to 20 minutes. Let the pan cool to room temperature on a wire rack.
Refrigerate until the bars are fully chilled, about one hour. Sprinkle them with confectioners sugar, if desired, before serving them.
