Line a large baking sheet with parchment and heat oven to 140C/120C fan/gas 1. For the meringues, put the egg whites and lemon juice in a large clean bowl (metal or ceramic is best) and whisk with hand beaters until the whites stand in stiff peaks, but are not at all dry or fluffy around the edges.
Add 1 tbsp of the sugar and whisk again until the whites return to stiff. Repeat until all the sugar has been used and the meringue is thick and glossy. Sprinkle in the hazelnuts; don’t stir.
Spoon 8 blobs of the meringue onto the lined baking sheet, aiming for something roughly egg- or rugby ball-shaped. As you push the meringue off the spoon, the hazelnut will ripple its way through the mixture. Make a small dip in the top of each meringue, ready to hold the cream and fruit later. Bake for 1¼ hrs or until pale golden and crisp. Leave to cool in the oven with the door ajar.
For the compote, gently heat everything together in a pan until the sugar dissolves, then bring to a simmer. Cover the pan and cook for 3 mins or until the fruit collapses but is still recognisable. Cool. Assemble meringues just before eating: whip the cream and use to top the meringues, then add spoonfuls of compote. Any leftover compote will keep in the fridge for a week or two.