4 egg whites
225g caster sugar
1 tsp vanilla extract
1 tsp cornflour
1 tbsp cocoa powder
1 tbsp chopped hazelnuts (optional)
Put the egg whites into a large clean bowl and whisk them until soft peaks form. Gradually add the sugar, little by little, whisking continuously. The mixture should be stiff, white, and glossy.
Now whisk in the vanilla extract and cornflour until well combined.
Swirl about a third of the cocoa powder into the mixture using a knife, then spoon small mounds, well spaced out, onto a baking sheet lined with baking parchment. Continue to add the cocoa powder so that each layer of mixture has a good amount of cocoa powder visible. At this point you can scatter chopped hazelnuts onto the mini meringues if desired.