Saku's Pistachio and Raspberry Marshmallow Biscuits

STEP 1: MAKE THE RASPBERRY JAM

In a small saucepan, combine the raspberries, granulated sugar, and lemon juice. Cook over medium heat, stirring and crushing the fruit, until it bubbles, thickens, and coats the back of a spoon, about 12–15 minutes. Pass through a fine sieve if you prefer a seedless jam. Cool completely; it will set further as it cools. You want a thick, spreadable jam, not a loose sauce.

STEP 2: MAKE THE PISTACHIO SABLÉ DOUGH

Grind the pistachios to a fine flour in a food processor, pulsing so they do not turn to paste. Beat the softened butter and icing sugar until pale and creamy. Beat in the egg yolk and vanilla. Add the ground pistachios, plain flour, cornflour, and salt, and mix on low just until a soft dough comes together. Bring into a disc, wrap, and chill for at least 30 minutes to firm up.

STEP 3: ROLL, CUT, AND BAKE

Preheat the oven to 180°C (350°F) and line two baking sheets. Roll the dough between two sheets of parchment to about 4 mm thick. Cut rounds with a 5 cm cutter, re-rolling scraps, to get an even number (about 20 rounds for 10 sandwiches). Chill the cut biscuits for 10 minutes to keep them crisp and prevent spreading. Bake for 12–15 minutes until just turning golden at the edges. Cool fully on the sheet before moving; sablés are fragile while warm.

STEP 4: BLOOM THE GELATINE AND START THE SYRUP

Sprinkle the gelatine over the cold water in a small bowl and leave to bloom for 5 minutes. In a small saucepan, combine the syrup sugar, water, and glucose. Bring to the boil over medium-high heat, stirring only until the sugar dissolves, then stop stirring and let it climb to 118°C (245°F) on a digital thermometer.

STEP 5: MAKE THE PISTACHIO MARSHMALLOW

As the syrup nears temperature, whisk the egg white in a stand mixer to soft peaks. With the mixer running on medium, pour the hot syrup down the side of the bowl in a slow, steady stream, not onto the whisk. Add the bloomed gelatine (melt it for a few seconds first if it has set) and whisk on high for 6–8 minutes until thick, glossy, and only just warm. Whisk in the pistachio paste, vanilla, and salt. The marshmallow should hold a soft ribbon but still be pipeable, so use it promptly.

STEP 6: SANDWICH THE BISCUITS

Pair up the biscuits by size. Transfer the marshmallow to a piping bag fitted with a plain round nozzle. Pipe a ring of marshmallow around the edge of the underside of half the biscuits, then spoon a little raspberry jam into the centre of each ring so the jam is held in by the marshmallow. Gently press a second biscuit on top so the filling reaches the edge without squeezing out.

STEP 7: SET AND FINISH

Roll or press the exposed marshmallow edge of each sandwich in finely chopped pistachios. Leave the biscuits to set, uncovered, for 2–3 hours at room temperature until the marshmallow is firm enough to handle cleanly. Dust very lightly with icing sugar to serve, echoing the refined finish the judges admired.