Preheat the oven to 210°F / 100°C (top and bottom heat). Separate the eggs and beat the egg whites in a clean, grease-free bowl. Halfway through, add the cornstarch (sifted), lemon juice, salt, and sugar, and continue beating until stiff peaks form.

Scoop the meringue onto a baking sheet lined with parchment paper and shape it using a spatula or spoon. A round shape is easiest. Don’t spread it too thin — smooth it out or create peaks, whichever look you prefer.

Melt the chocolate in a heatproof bowl over simmering water (double boiler), let it cool slightly, and gently fold it through the meringue for a marbled effect. Stop as soon as you see streaks; you don’t want a completely brown mixture.

Place the pavlova in the oven and bake for about 2 to 2.5 hours. The outside should feel dry and slightly crisp.

Turn the oven off and let the pavlova cool completely inside the oven with the door propped open (use a wooden spoon). Carefully remove it from the baking sheet.

To make the ganache, heat the heavy cream in a small saucepan until just below boiling. Pour over the chopped chocolate and stir until smooth. Let cool.

When ready to serve, whip the heavy cream with sugar. Spoon generous dollops on top of the pavlova and sprinkle with chopped nuts (hazelnuts, walnuts, pecans, pistachios). Finish with a drizzle of ganache — a small piping bag works best, but a spoon also does the job.