Preheat oven to 175°C. Grease and line a 24 cm springform tin. Set aside.
Whisk the egg whites until thick (about 2 minutes) then gradually whisk in the caster sugar.
Fold through the vanilla, yoghurt, ground pistachios and baking powder. Pour the mixture into the prepared tin and smooth the top. Arrange the sliced peaches over the top and scatter half of the berries between the peach slices.
Bake for 40-50 minutes, or until golden and cooked through. Cool completely before removing from the tin.
To serve, dust generously with icing sugar and scatter over the remaining berries.
If you’re going out foraging be 100% certain that what you’re picking is edible. When in doubt, don’t pick it – or consult an expert.