Heat oven to 140C/fan 120C/gas 1, and line two flat baking sheets with baking parchment. Whizz about two-thirds of the toasted almonds in a food processor until chopped. Don’t let them start to look greasy or clump together – they should still be in pieces rather than ground. Roughly chop the remaining third with a knife.
Stir the sugars together. Using an electric hand whisk, beat the egg whites in a large bowl until stiff, then add the sugar in three batches, beating the mixture back to stiff after each addition. Add the cornflour and vinegar, and keep going until the meringue mixture is glossy and so stiff that the beaters begin to feel heavy when stirring – this can take up to 5 mins.
Quickly fold in all of the finely chopped nuts and most of the roughly chopped with a spatula, then divide the mixture between the two baking sheets. Spread both into 20cm circles, then scatter the remaining chopped nuts over. Bake for 1 hr, then turn the oven off and leave the meringues inside to cool for at least 1 hr. Leave the oven door closed (this will help to prevent them cracking). Will keep overnight in an airtight container, or freeze, wrapped in cling film, for up to 1 month.
For the strawberry sauce, purée 600g of the strawberries in a food processor or blender. Press through a sieve to remove the seeds, then sweeten with 2 tbsp of the icing sugar. Can be made up to 1 day ahead. Sieve the remaining icing sugar into the double cream, whip until it just holds its shape, then carefully swirl through two-thirds of the sauce.
To serve, slide one of the meringues off its
baking parchment onto a serving plate, then
spread over half the cream. Place the second
meringue on top, pile over the rest of the
cream and top with the remaining
strawberries. Dust with a little more icing
sugar if you like, and serve the leftover
strawberry sauce alongside.