Petite Lemon Curd Cookies

Name: Petite Lemon Curd Cookies
Ingredients: Ingredients for basic butter cookies; 1 1/2 cups confectioners sugar for dredging and dusting; 3/4 cup fresh lemon juice; 1 tablespoon finely grated fresh lemon zest; 3/4 cup granulated sugar; 1 stick (1/2 cup) unsalted butter, cut into bits; 2 tablespoons cornstarch; 1/2 teaspoon salt; 4 large egg yolks; Special equipment: a 1 1/4-inch round cookie cutter; a pastry bag fitted with small plain tip or a heavy-duty sealable plastic bag (not pleated)