Citrus Marshmallow Roulade with Chocolate Ganache

1. Stage

Lightly spray a 10- by 12-inch baking tin with oil, line the base and two long sides with non-stick baking paper and lightly spray the paper with oil. Set aside 1/3 cup water in a small, deep heavy-based saucepan. Stir over low heat until the sugar dissolves. Bring to the boil and simmer, without stirring, until the syrup reaches 260 degrees F on a sugar thermometer (this is the upper end of the hard-ball stage). The amount of syrup is quite small, so ensure your thermometer is immersed in the syrup without touching the base of the pan.

2. Stage

Meanwhile, slowly sprinkle the gelatin over 1/3 cold water in a shallow microwave-safe bowl and set aside for 5 minutes. Heat in the microwave for 30–45 seconds on High (100 percent), or until the gelatin has dissolved.

3. Stage

When the sugar syrup reaches 239 degrees F, whisk the egg white in an electric mixer with a whisk attachment on medium speed. When frothy, increase the speed to medium–high and gradually add the reserved sugar, whisking until thick and glossy. Keep the mixer running on medium speed. When the sugar syrup reaches 260 degrees F, turn off the heat. When the bubbles subside, carefully add the dissolved gelatin – take care, as the mixture may bubble up.

4. Stage

Increase the mixer speed to medium–high and gradually pour the hot syrup mixture down the inside of the bowl in a thin, steady stream. Increase the speed to high and continue whisking until the mixture is thick. Add the orange zest and whisk until the mixture is very thick and holds its shape, about 8–10 minutes, depending on your mixer. The outside of the bowl should almost be at room temperature.

5. Stage

Use a spatula to scrape the marshmallow mixture into the prepared tin and smooth the surface. Stand for 1–2 hours, until set.

6. Stage

Meanwhile, to make the filling, whip the cream until firm peaks just form. Fold in the curd, then cover and refrigerate until required. To make the ganache, heat the cream in a small saucepan until it just comes to a simmer. Remove from the heat, add the chocolate and stir until smooth. Set aside at room temperature.

7. Stage

Turn the marshmallow out onto a piece of non-stick baking paper lightly sprayed with oil, with a short side facing you. Spread the filling over the marshmallow, leaving a 2 inch border on the short side furthest from you. Roll up the marshmallow, starting at the short side closest to you, to enclose the filling. Place on a serving plate, seam side down. Drizzle with the ganache and top with the praline shards.