Dulce de leche marshmallow biscuits

1.For brown sugar biscuits, preheat oven to 180C. Beat butter, sugar and vanilla seeds in an electric mixer until light and fluffy (4-5 minutes), then scrape down sides of bowl, add eggs and beat to combine. Sieve in flours, baking powder, bicarbonate of soda and a pinch of salt, and mix to combine. Divide dough in half, roll out on a lightly floured surface to 3mm thick, then place on baking trays lined with baking paper and refrigerate until firm (30 minutes). Cut out 7cm rounds with a biscuit cutter and place on baking trays lined with baking paper. Bake until dark golden (8-10 minutes), then cool completely.

2.For marshmallow, stir glucose, 250gm sugar and 100ml water in a small saucepan over medium-high heat until sugar dissolves, then bring to the boil and cook until mixture reaches 118C on a sugar thermometer (3-5 minutes). Meanwhile, squeeze water from gelatine, then place in a bowl over a saucepan of simmering water to melt. When sugar syrup reaches 118C, whisk eggwhite and a pinch of salt in an electric mixer until soft peaks form, then gradually add remaining sugar and whisk until glossy. Continue cooking sugar syrup until it reaches 127C (6-8 minutes), then mix in gelatine and gradually add syrup to eggwhite mixture, whisking continuously on medium speed. Add vanilla seeds and whisk at high speed until cool and thick (10 minutes). Spoon into a 20cm x 30cm cake tin lined with baking paper, smooth top with a wet palette knife and stand at room temperature until set (2 hours). Turn out of tin and cut into 7cm rounds with a biscuit cutter dipped in icing sugar.

3.Spread biscuit bases thickly with dulce de leche, then top half with marshmallow rounds. Sandwich with remaining biscuits and drizzle or spread with chocolate, or half-dip biscuits in chocolate, shaking off excess, and set aside to set (15 minutes). Biscuits will keep in an airtight container for 3 days, or refrigerated for up to a week.