Meanwhile, prepare the emon filling:
In a 2-quart saucepan, mix 1 cup granulated sugar, the lemon juice, water, and cornstarch until well combined. Heat the mixture to boiling over medium-high heat, stirring constantly; cook 1 to 2 minutes longer or until the mixture thickens. Remove from the heat.

In a medium-size bowl, with a wire whisk, beat the remaining 1/2 cup granulated sugar, eggs and the lemon rind until thick and lemon colored. Slowly beat the lemon mixture into the egg mixture until well combined. Pour the filling into the prepared crust.

Bake the cookies 15 to 20 minutes, or until the filling is firm. Cool the cookies completely in the pan on a wire rack.

Cut the cookies into 6 rectangular bars. Place the bars on a serving plate. Sprinkle confectioners sugar over the cookies. Create stripes across the bars with the red gel frosting. Place 6 blueberries in the top corner of each bar.