Combine all of the ingredients in a small saucepan. Set over medium-low heat, and whisk well, allowing to thicken for about 4-5 minutes. Once thickened, remove from the heat and set aside allow to cool completely.

Preheat the oven to 350 F and line a sheet pan with parchment paper lightly greased with oil.

Start with the crust by mixing together the two flours, and then stirring in the wet ingredients until well combined.

Using a tbsp-sized scoop, scoop the dough into a tbsp and roll into a ball. Set the ball of dough onto the baking sheet and press your thumb into the center to make a thumbprint indentation. Repeat for all of the dough.

Very carefully scoop about 1-2 tsp worth of lemon curd into the thumbprint indentation of each cookie, being careful not to overfill. The lemon curd is very sticky and thick and can get messy so clean up any spills of the lemon curd with your fingers.

Transfer to the preheated oven and bake for 12 minutes or until firm and baked through and the lemon curd is set.

Allow cooling for a few minutes before carefully transfer to a cooling rack. Allow cooling further before topping with optional powdered sugar. Serve fresh (these are best fresh!) or keep in the fridge for 1-2 days.