Peel the small potatoes and cook them whole in salted water for 20 minutes.
In the meantime, clean the chanterelles, but do not wash them, cut off the ends of the stems and cut large mushrooms in half lengthways and crossways. Cap the small red onions at both ends, peel and cut into small pieces. Wash the celery, pluck the leaves and chop finely.
Drain the water from the potatoes, add 2 tablespoons of the butter to the potatoes and toss with the lid on without heat. Add 1 tablespoon of the celery leaves and prepare the potatoes warm.
Melt the remaining butter in a pan and fry the onion pieces until translucent, add the chanterelles and stir-fry for 3 minutes. Season to taste with salt or chicken stock, pepper and nutmeg, add a tablespoon of the celery leaves. Mix well again.
Arrange on a serving plate with the potatoes, garnish with the remaining celery leaves and serve warm.