For the Italian meringue:
1 1/4 cups caster (superfine) sugar
7 tbsp water
5 egg whites
1/2 tsp vanilla bean paste
For the candied walnuts:
1 cup caster (superfine) sugar
3/4 cup walnut halves
1/2 tsp sea salt flakes
10 digestive biscuits
10 clementines, peeled and pith removed
3 1/2 cups white chocolate, melted
1. To make the meringue: In a saucepan over medium heat, add sugar and water. Stir until sugar is dissolved, then bring to a fast boil. As soon as the syrup reaches 230 degrees, begin to whisk the egg whites until they form stiff peaks. When the syrup reaches 250 degrees pour it onto the egg whites in a thin, steady stream as you continue to whisk. Be careful not to pour the hot syrup directly onto the beaters. Continue to whisk the meringue until it has cooled. Add the vanilla and whisk to combine. It should be shiny and stiff. Allow to cool completely and then spoon into a piping bag fitted with a large circular nozzle. Set aside.
2. To make the candied walnuts: Place the sugar into a saucepan and cook, without stirring, until the sugar turns a golden amber color, 6 to 8 minutes.
3. While the sugar is cooking, lay the walnuts on a baking sheet lined with greaseproof paper. When the sugar has turned golden, pour it over the walnuts, making sure they are all covered. Sprinkle with sea salt and then set aside to cool. Once cool, blitz the walnuts in a food processor until they resemble breadcrumbs.
4. To assemble: Attach a clementine to the center of a biscuit, using some meringue as ‘glue’. Pipe the meringue around the clementine in a spiral shape, then repeat until all the clementines are covered. Allow to set for 5 minutes, then transfer to a wire rack set over a rimmed baking tray.
5. Pour the melted white chocolate over the meringue-covered clementines to cover completely. Once all the bombes are covered, sprinkle with the candied walnuts and serve straight away.