Serves: 35 pieces
1⁄2 cup icing sugar, sifted
1⁄2 cup cornflour
1 tablespoon liquid glucose
2 tablespoons gelatine
2 egg whites
1 teaspoon geranium water,
or to taste red food colouring, optional
2 tablespoons dried rose petals
Lightly oil a 20x30x3cm deep cake tin. Combine the icing sugar and cornflour and use 2 tablespoons to dust the inside of the tin. Combine the sugar, glucose and 200ml of the water in a large heavybased saucepan and stir over a low heat until the sugar dissolves. Bring to the boil without stirring and cook until the syrup reaches hard-ball stage (121ºC on a sugar thermometer).
Meanwhile, sprinkle the gelatine over the other 200ml of water in a small heatproof bowl and let stand for 10 minutes. Place the bowl in a small saucepan of simmering water and stir until the gelatine is completely dissolved.
Add the liquid gelatine to the sugar syrup, taking care as the mixture will splutter. Using an electric mixer, beat the egg whites until stiff peaks form, then, beating constantly, gradually pour the hot syrup down the side of the bowl in a thin, steady stream. Add the geranium water and a drop of red food colouring, if using, then whisk until the mixture is thick and holds its shape.
Sprinkle the base of the prepared tin with half the dried rose petals, then pour in the marshmallow mixture. Smooth the top, sprinkle with the remaining rose petals and let stand for 2 hours. Dust a work surface with half the remaining icing sugar mixture and turn out the set marshmallow. Using a large knife dipped in hot water, cut into squares, then toss each piece to coat in the remaining sugar mixture. Stand for 1 hour to allow the surface to dry, then store in an airtight container for up to 1 week. Makes about 35 pieces