Step 1

Preheat the oven to 190ºC, gas mark 5 with the shelves set towards the middle. Line 3 baking sheets with baking parchment, then draw a circle, 23cm diameter, on each (use a cake tin as a guide). Tip the hazelnuts onto a small baking tray and toast in the oven for 4 minutes, until light golden. Leave to cool, then finely chop.

Step 2

Spread the caster sugar over another baking tray and heat for 5 minutes until hot to the touch. As it heats, tip the egg whites and a pinch of salt into the bowl of a stand mixer fitted with a whisk attachment (or use a large bowl and electric hand mixer), then whisk until they almost hold a stiff peak.

Step 3

Quickly and carefully tip the hot caster sugar into the beaten egg whites. Whisk for 1 minute, then scrape down the sides of the bowl with a rubber spatula. Add the coffee and continue to whisk on a fast speed for about 3 minutes, until the meringue is stiff and glossy and the sugar has dissolved.

Step 4

Gradually add the brown sugar, 1 tbsp at a time, whisking continuously and scraping down the bowl with the rubber spatula to ensure everything is combined. Whisk on full speed for 2 minutes more, until the sugar is incorporated and the meringue has cooled. It should be silky smooth. If the sugar hasn’t completely dissolved, mix for another minute or so

Step 5

Lower the oven temperature to 110ºC, gas mark ¼-½. Divide the meringue evenly between the 3 baking sheets, then gently spread into 23cm discs using a palette knife. Sprinkle the chopped hazelnuts over each disc. Bake, swapping the trays from top to bottom halfway, for 1 hour 15 minutes-1 hour 30 minutes, until crisp. Turn the oven off, then let the meringues cool inside for 45 minutes.

Step 6

While the meringues are cooling, prepare the filling. Melt the chocolate in a heatproof bowl set over a pan of barely simmering water. Stir until smooth, then set aside to cool slightly. Keep the pan of water for the next step.

Step 7

Put the egg yolks in a medium-sized, heatproof glass or ceramic bowl and set aside. Tip the caster sugar and 3 tbsp water into a small saucepan and set over a low heat to dissolve the sugar. Bring to the boil and simmer for 30 seconds to thicken slightly. Add the coffee (or liqueur), then pour the syrup over the egg yolks and whisk until smooth. Add a pinch of salt and set the bowl over a pan of simmering water (the bottom shouldn’t touch the water). Whisk, using a balloon whisk, for 2-3 minutes until pale and thickened.

Step 8

Remove the bowl from the heat and whisk for 2-3 minutes more, until the mixture is cool and the consistency of softly whipped cream. Add the melted chocolate and stir gently until smooth, then add 100ml cream and mix gently to combine. Chill in the fridge for about 1 hour, until stiff enough to spread.

Step 9

Whip the remaining 500ml cream to soft peaks. Place 1 meringue onto a serving plate and spread with ½ the chocolate cream. Top with ½ the whipped cream. Top with the second meringue and spread over the remaining chocolate cream, followed by the remaining whipped double cream. Top with the final meringue and sprinkle over the chocolate hazelnuts, if liked (see tip). Dust with the cocoa powder, then serve.