Preheat the oven to 170C/325F. Line an 8 x 8-inch pan with parchment paper and set aside.
In a mixing bowl, add the flour, allulose, salt, vanilla, and butter, and mix together until combined. Transfer it into the lined pan and press down until mostly smooth. Place the crust in the oven and bake for 20-22 minutes, or until it begins to go golden.
While the crust is baking, prepare the filling. In a mixing bowl, add the flour and allulose and mix well. Add the eggs and lemon juice, and whisk until smooth.
Pour the lemon filling over the par-baked crust and spread out evenly. Place back into the oven for 23-25 minutes, or until the filling remains firm once lightly shaken.
Remove the lemon bars from the oven and let them cool completely. Once cool, sift the powdered sweetener all over the top. Refrigerate the bars to firm up more, before slicing into bars.
Video
Notes
Tips: See my recipe tips above for the best lemon bars.
Leftovers: Keep in the fridge for one week or the freezer for 6 months.