Preheat oven to 375 degrees. Unroll pastry onto a lined or greased baking sheet or parchment paper on baking sheet. In a small sauce pan mix apricot jam and water together. Boil until well combined. Remove pits from the nectarines. Slice each one thinly into about 12 wedges. Arrange the fruit in concentric circles on the pastry.  Scatter the aroniaberries over the fruit and sprinkle sugar over the top. Drizzle the apricot mixture of the nectarines and aroniaberries. Fold the crust over the filling. Bake for 45 minutes until pastry is golden brown and filling is bubbling slightly. Serve warm with whipped cream.