Chocolate swirl meringues with praline and chocolate caramel sauce

Method

1. Heat the oven to 120°C/100°C fan/gas ½.  Put the egg whites and both sugars in a large heatproof bowl set over a pan of barely simmering water. Using an electric mixer, whisk the egg whites and sugar on a low speed, over the heat, until the sugar starts to dissolve. Turn up the speed and continue to whisk until you have a smooth, thick, glossy meringue and all the sugar has dissolved. Remove from the heat, then continue whisking until cool (about 10 minutes).
2. Drizzle the melted chocolate into the cooled meringue mixture, then quickly fold, once or twice, to swirl the chocolate through the meringue. Spoon 10 mounds of meringue (roughly 8cm wide) onto 2 of the baking sheets, then make a dip in the middle of each pile. Bake in the oven for 1 hour, then turn the oven off and leave the meringue to cool inside it for 2 hours.
3. For the praline, toast the hazelnuts in a dry frying pan over a medium heat for a few minutes until turning golden. Transfer to a board, then roughly chop.
4. With the frying pan over a medium-high heat, sprinkle in the 150g caster sugar, a spoonful at a time, shaking the pan and adding another spoonful as soon as the first dissolves. Continue until all the sugar has been added and the caramel has turned a deep golden colour.
5. Gently stir in the chopped hazelnuts until just coated, then tip the mixture onto the remaining lined baking sheet and use a spatula to spread as thinly as possible. Set aside until completely cool, then pulse in a food processor (or put in a food bag and bash with a rolling pin) to a rough crumb.
6. For the chocolate caramel sauce, put the 100g sugar in a pan with 2 tbsp water and heat gently until dissolved. Bubble until the mixture turns a deep caramel colour, then quickly whisk in the butter and dark chocolate until melted and smooth (be careful as it might spit). Whisk in the 50ml double cream to make a smooth, glossy sauce. Once cooled slightly, add a pinch of salt to taste.
7. Whisk the yogurt with the 200ml double cream, then fold in most of the hazelnut praline. To serve, top each meringue with a dollop of cream and a drizzle of caramel sauce (see tip). Add a raspberry, if you like, and scatter over the remaining praline.