Makes 12 pieces
50g/2oz/½ cup gluten-free cornflour (cornstarch)
125g/4oz/1 cup rice flour
75g/3oz/¾ cup ground almonds
75g/3oz/6 tbsp caster (superfine) sugar, plus extra to sprinkle
175g/6oz/¾ cup butter, diced
grated zest of ½ orange
1 tbsp chopped fresh rosemary
1 Preheat the oven to 170°C/325°F/Gas 3.
2 Put the cornflour and rice flour in a bowl. Add the ground almonds and sugar, then rub in the butter with your fingertips until the mixture resembles breadcrumbs.
3 Add the orange zest and rosemary and stir until the mixture sticks together to form a ball. Tip into a 25cm/10in loose-bottomed tart tin and press down evenly. Mark the edge of the shortbread with the tines of a fork and prick the centre.
4 Bake in the oven for 30–35 minutes until the shortbread is pale golden. Cool in the tin for a few minutes, then mark into 12 wedges. Sprinkle with caster sugar and set aside to cool completely. Remove from the tin and cut into wedges. Store in an airtight tin for up to three days.