In a mixing bowl, whisk together the sugar, 2 tablespoons flour, lemon juice, lemon zest, eggs and egg white; whisk until thoroughly incorporated and smooth.
Remove baked crust from oven and let stand 2 minutes.
Reduce oven temperature to 325F.
Arrange fresh raspberries over the baked crust.
Pour lemon mixture over raspberries.
Bake for 22 to 25 minutes, or until topping is set.
Remove from oven and cool completely in pan on a wire rack.
Cover and chill in the freezer for at least 1 hour.
Optional: Place bottom of baking dish in a larger pan filled with hot water so it's easier to cut out the squares. Keep in hot water for about 30 seconds.
Sprinkle bars with powdered sugar.
Cut and serve.