125g unsalted butter, softened
1/2 cup caster sugar
1 tsp vanilla extract
1 free-range egg
1 1/4 cups gluten-free plain flour, plus a little extra for dusting
2 Tbsp white rice flour
1 tsp xanthan gum
80g unsalted butter
2/3 cup icing sugar mixture, plus extra, to dust
2 Tbsp passionfruit pulp
Preheat oven to 150°C fan-forced (170°C conventional). Line 2 oven trays with baking paper.
Combine butter, sugar and vanilla in a medium bowl and beat with the paddle attachment of an electric mixer for 2-3 minutes, until combined. Add egg and beat until just combined. Stir in sifted flours and xanthan gum, in 2 batches. Cover and chill for 10 minutes, if needed, to firm up dough slightly.
Using wet hands, roll tablespoonfuls of mixture into
16 balls (see Cook’s tip, below, if you want to make smaller biscuits). Arrange balls on prepared trays spaced 5cm apart and flatten slightly with a fork dusted in a little extra gluten-free plain flour.
Bake cookies for 20 minutes, or until bases are light golden and tops are still pale. Cool fully on trays.
To make passionfruit buttercream, beat butter and sifted icing sugar mixture in a small bowl with an electric mixer until pale and fluffy. Beat in passionfruit pulp.
Sandwich biscuits with a tablespoon of buttercream. Dust tops with extra sifted icing sugar. Serve.