Preheat oven to 350 degrees Place a large enough piece of parchment paper in an 8x8 baking dish to create handles up the sides of the dish.
To make crust, place ghee, honey, vanilla and egg in the bowl of an electric mixer. Mix on medium setting until combined. Add in cassava flour, salt and zest. Mix once more until just incorporated.
Press crust mixture evenly into the prepared baking dish.
Bake in preheated oven for 15 minutes.
While crust is baking, add filling ingredients to the bowl of an electric mixer. Mix until combined. Pour filling ingredients over the baked crust and place it back in the oven for 25 minutes or until baked through.
Place lemon bars on a cooling rack until completely cooled, then transfer to the refrigerator to chill overnight.