Whisk the egg whites until they start forming stiff peaks, then whisk in the cream of tartar. Slowly add a dessert spoon at a time of icing sugar, waiting until each spoonful is incorporated into the meringue, until you have a thick, glossy mixture. Pour into three lined 20cm cake tins.
Bake in a 140°C/280°F oven for an hour, then turn off the oven and leave in for another hour. Allow to cool and peel off the baking paper.
Place one of the meringue circles on a board then top with a layer of whipped cream and berries, then repeat. On the final layer place berries and more whipped cream. Serve with a strawberry coulis.