In a mixing bowl, whisk together the all-purpose flour, almond flour and baking powder.
In a separate bowl, beat the butter, sweetener and lemon zest with an electric mixer on medium until creamy, about 2 - 3 minutes. Beat in the egg yolk until combined.
Gradually beat the dry flour mixture into the butter mixture on low, just until combined.
Divide the dough in half and roll into two logs about 10 - 12-inches long. Wrap tightly with plastic wrap and refrigerate until firm, 1 - 2 hours.
When you are ready to bake the cookies, preheat oven to 350F degrees and line cookie sheets with parchment paper or use silicone liners. Remove the dough from the refrigerator, unwrap and cut into 1/2-inch slices and place on prepared cookie sheets. (You should have about 30 cookies.)
Bake for about 15 minutes, or until cookies turn golden around the edges. Remove from oven and allow to cool for a couple of minutes before moving cookies to a wire rack to cool completely.
Store cookies in an airtight container at room temperature.
Notes
Serving size: 1 sugar-free lemon shortbread cookieWW 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.)WW PointsPlus (Old plan): 4