In a blender, mix 1 of the pints of blackberries with the water and lemon juice. Purée until smooth. Pass the purée through a fine sieve, pressing down with the back of a ladle. Adjust the flavor with either more lemon juice or a little sugar. Reserve this coulis.
Heat the grill to medium high. In a shallow bowl or lipped plate, stir the melted butter, honey, and cinnamon. Cut each nectarine in half and remove the pit. Slice a bit off of the side opposite the pit so that the fruit will lay flat when serving. Roll each half in the melted butter mixture. Grill, pit side down, until the fruit is softened and the pit side begins to darken and caramelize, about 4 minutes.
Put a nectarine half (pit side up) at the center of each plate. Drizzle some of the coulis around the fruit and sprinkle with the fresh blackberries. Top each nectarine while still warm with a scoop of ice cream. Garnish with a crisp butter cookie and a sprig of fresh mint, if you like. Serve immediately, while the ice cream begins to soften but before it melts.
nutrition information (per serving):
Photo: Judi Rutz