Soak gelatine in cold water. Separate eggs. Combine milk with butter, vanilla, sugar and salt, bring to a boil. Add semolina gradually and boil, stirring. Remove from heat and let semolina swell for a few minutes. Add well-squeezed gelatine and egg yolks into warm mixture. Beat egg whites until stiff and fold into mixture. Pour into pudding pan, cool completely and refrigerate for about 3 hours.
Invert onto a plate and garnish with nectarine fillets, if desired. Serve.