Preheat oven to 375F degrees and spray an 8-inch square baking pan with nonstick spray. For easier removal and cleanup, line baking pan with parchment and lightly grease with nonstick spray.
Prepare the Crust:
Whisk together 1 cup flour, 2 tablespoons Truvia Baking Blend and 1/4 teaspoon salt in a medium bowl. Cut in cold butter with pastry blender, or a fork, until mixture forms coarse crumbles.
Add 2 tablespoons buttermilk and give mixture a gentle stir. Press flour mixture into bottom of prepared pan and place pan in refrigerator for 15 minutes to chill.
Bake the crust until lightly golden, about 15 to 20 minutes.
Prepare the Lemon Topping:
Meanwhile, whisk the eggs, egg white, 3 tablespoons flour and 8 tablespoons Truvia Baking Blend in a large bowl. Whisk in the lemon juice, 1/3 cup buttermilk and lemon zest until thoroughly combined.
Pour lemon mixture over hot crust and sprinkle the blueberries over the top.
Lower oven to 350F degrees and continue baking until top is just barely set, about 18 to 20 minutes.
Cool completely in pan on wire rack before moving to the refrigerator until ready to serve.
Before serving, cut bars into 12 pieces and sift powdered sugar over the top, if desired.
Store any leftover lemon bars in an airtight container in the refrigerator.
Notes
Serving size: 1 lemon blueberry bar (1/12th recipe)WW Points: 3Check the WW Points for this recipe and track it in the WW app. (Must be logged into WW on a smartphone or tablet.)3PointsPlus (Old plan)To save a little time, the lemon topping can be prepared ahead and stored in an airtight container in the refrigerator. When you are ready to bake the bars, prepare and bake the crust. Give the lemon mixture a good stir and pour over hot crust, then bake as directed.