- Preheat oven to 350°F. Grease and flour a 9x13x2 inch baking pan.
- Cut butter into 1/2-inch pieces.
- In a food processor process all shortbread base ingredients until mixture begins to form small lumps.
- Sprinkle mixture into a baking pan and with a metal spatula press evenly onto bottom.
- Bake shortbread in middle of oven until golden, about 20 minutes.
- While shortbread is baking, prepare topping.
- Reduce oven temperature to 300°F.
- In a bowl whisk together eggs and granulated sugar until combined well and stir in lemon juice and flour.
- Pour lemon mixture over hot shortbread.
- And bake in middle of oven until set, about 30 minutes.
- Cool completely in pan and cut into 24 bars.
- Bar cookies keep, covered and chilled, 3 days.
- Sift confectioners' sugar over bars before serving.