Preheat the oven to 140C (275F), gas 1 and line a flat baking sheet with foil or baking parchment.

Whisk the egg whites with a pinch of salt until stiff, then add 225g of the sugar, a tablespoon at a time, whisking it in well between each addition. The mixture will be very thick and shiny.

When all the sugar is incorporated add the cornflour, cocoa powder, vanilla essence and vinegar and whisk well again.

Pile the mixture onto the lined baking sheet and mould it into a flattish round shape, roughly 20-25cm across and 4cm deep. Make a dip in the middle using a metal spoon.

Cook for 45 minutes, then turn the oven off leaving the pavlova inside until cold, without opening the door.

Carefully peel off the foil.

Put the frozen berries into a non-reactive pan with the rest of the sugar. Warm gently over a low heat, just until the fruit has thawed, trying not to break it up.

Tip into a sieve over a bowl and leave to drain for 15 minutes or so. Pour the juice back into the pan and boil fast, giving it the odd stir, until it has reduced to a syrupy consistency and just coats the back of the wooden spoon. Leave to cool. It will thicken up much more when cold.

Melt the chocolate in a small bowl suspended over a pan of hot water or in a microwave and carefully brush over the inside of the pavlova. Dust the outside with cocoa powder, then icing sugar (I forgot to do this!)

Whip the cream lightly into soft peaks and spoon into the centre of the pavlova. Mix the berries and the sauce together (this is when I added the fresh raspberries) and spoon over the top.