Cook the pasta in plenty of boiling salted water for about 11 minutes. Meanwhile wash the peaches, dab dry, cut in half and remove the stone. Cut peach halves into thin slices.
Pour the pasta onto a sieve, rinse with cold water, drain and allow to cool. Clean and wash spring onions and cut into fine rings. Blanch for about 1 minute in boiling salted water and drain on a sieve.
Stir mango chutney and buttermilk until smooth and mix with penne, peaches and spring onions. Leave to stand for approx. 30 minutes. Season to taste with curry and salt just before serving. Carefully wash the nasturtium, drain and sprinkle over the salad.