Preheat oven to 180ºC. Line a square 20cm tin with baking paper.
To make the shortbread base, combine flour, rice flour, Natvia and salt in a bowl. Add butter and rub between fingers until mixture looks like wet sand.
Pour into lined tin and press down with the back of a spoon. Bake for 12 minutes until golden.
In the meantime, make the mandarin curd by add all ingredients into a large bowl and whisking together until well combined.
Pour over the top of the cooked shortbread and place back into the oven for 20 minutes until the curd has set.
Remove from the oven and cool for at least two hours before sliceing and serving.
Comments