1. Pre-heat the oven to 160°C. Line two flat baking sheets with greaseproof paper.
2. Place all the ingredients for the biscuits into a JTC Omniblend and give it a pulse. Tip the mixture out onto a clean work surface and use you hands to bring it together, but don't knead it.
3. Place the dough into a piping bag fitted with a large, star-tip piping nozzle and pipe an even number of rosettes or swirls onto the sheets. Try to make sure they’re all a similar size to make sandwiching them together easier later on.
4. Bake for 18-20 minutes or until lightly golden. Allow to cool on the sheet for 10 minutes, then transfer to a wire rack to cool completely.
5. To make the filling, beat all the ingredients together until pale and fluffy.
6. Pile the buttercream into a piping bag fitted with a star tip and pipe onto half of the biscuits before sandwiching with another, or simply spread the filling on with a teaspoon and place another on top.