Cook the Book: Lemon Curd Squares with Rosemary

Name: Cook the Book: Lemon Curd Squares with Rosemary
Ingredients: For the Shortbread:; 3 cups all-purpose flour; 1 1/2 cups (3 sticks) unsalted butter; 1/2 cup granulated sugar; 1/3 cup confectioners' sugar, plus additional for sprinkling; 1 tablespoon chopped fresh rosemary; 1 teaspoon finely grated lemon zest; For the Lemon Curd:; 6 large eggs, lightly beaten; 1 1/2 cups granulated sugar; 2/3 cup freshly squeezed lemon juice (3 to 4 lemons); 1/4 cup all-purpose flour; 1 tablespoon finely grated lemon zest; Pinch kosher salt