1. Spray a 9 by 4 1/2 by 2 3/4-inch loaf pan with cooking spray. Line with plastic wrap, overlapping edges; set aside. Coarsely chop 2 cups pistachio nuts; combine with milk in a medium saucepan. Bring to a gentle boil. Remove from heat, and steep for 1 hour.

2. Combine egg yolks and sugar in bowl of electric mixer. Using whip attachment, beat at medium-high speed until very thick and pale yellow, 2 to 3 minutes. Meanwhile, strain milk; discard nuts. Bring milk back to a simmer.

3. Whisk half of the hot milk into the sugar mixture, and return to saucepan. Cook over medium-low heat, stirring, until thick enough to coat a wooden spoon, 8 to 10 minutes.

4. Remove from heat. Stir in cream; pass through a fine strainer. Pour into a medium bowl; chill over ice bath. Stir in rose water.

5. Pour half of mixture into an ice-cream maker, and freeze according to manufacturer's instructions. Before removing ice cream, add 1/2 cup whole pistachio nuts, churning until incorporated, about 30 seconds. Spoon ice cream into prepared pan, and transfer to freezer. Freeze remaining mixture in ice-cream maker, adding remaining pistachio nuts at end. Remove pan from freezer; add second layer of ice cream. Cover with overlapping plastic wrap; freeze.

6. To serve, invert loaf pan onto serving plate. Cover bottom and sides of pan with cold wet towel; rub for about 1 minute. Pull plastic wrap down; ice cream will slide from pan. Remove plastic wrap, slice, and serve.