Preheat oven to 350°F/175C. Line an 8 x 8”/20cm x 20cm pan with parchment (or grease well).
In a small bowl, combine flour, cornstarch, powdered sugar, baking soda, and salt. Stir to distribute and set aside.
In a large bowl, combine oil and apple sauce. Beat until well emulsified.
Add granulated sugar and vanilla. Beat together on low speed for 1-2 minutes until well emulsified.
Stir in the flour mixture until completely incorporated.
Divide dough into thirds. Press 2/3 of the dough into the pan in an even layer. Spread the lemon curd in an even layer on top. Crumble up the remaining dough and scatter on top of the lemon curd.
Bake for 22-25 minutes until dough on top is just barely starting to go golden brown on the edges.
Cool in the pan before cutting.
Store at room temperature in an airtight container for up to 3 days or in the freezer for 1 month. Bring to room temperature before eating.
Notes
Texture/taste Notes: A soft cookie base with a decadent layer of tangy lemon curd, and more cookie dough crumbled on top for a crust lover’s alternative to a lemon bar. This is a great way to use up the lemon curd you got enthusiastic about making but don’t eat enough toast or scones for. The dough base is lightly sweet, with just enough chew to blend with the lemon curd. The recipe can also be adapted to any other flavour of curd or even used with regular jams.Oil choice: Any unsaturated oil will work in this recipe. The best choices are very neutral flavored oils like canola, sunflower, or vegetable. Coconut oil should not be used as it will react with the applesauce and resolidify, creating uneven pockets of moisture.Flavor Variations: Lemon curd can be replaced with any other flavor of curd. For best results swap out the lemon zest for other zests when applicable. Lemon curd can also be replaced with any type of jam.