Preheat oven to 180c.
Line a baking tray with parchment/baking paper and set aside.
In a bowl whisk together plain flour, corn flour and salt then set aside.
225 g plain flour (all-purpose flour), 45 g corn flour (corn starch), pinch of fine salt
Place butter and icing sugar into a large bowl, and using a hand held mixer (or stand mixer with a paddle attachment) cream together until the mixture is pale yellow and creamy.
200 g unsalted butter, 85 g icing sugar (confectioners sugar/powdered sugar)
Mix in vanilla extract.
¾ teaspoon vanilla extract
Add the reserved flour to the butter mixture a third at a time, beating each time until just incorporated.
Scrape in any unmixed flour from the sides of the bowl with a spatula.
Using a tablespoon measure as a guide, roll cookie dough into balls and place on the prepared baking tray.
Use your knuckle (or something less fun like a measuring spoon maybe) to press down slowly on the cookie dough balls to flatten slightly and make an indent.
Fill each indent with lemon curd, then place in the oven to bake.
⅓ cup lemon curd
Bake for 9 - 10 minutes, or until they just start to go brown around the edges.
Allow to cool for 10 minutes to firm up, then remove to a wire rack to finish cooling.
Dust with a little extra icing sugar if you wish.