Finely grind pistachios and 1/4 cup of the sugar in a food processor.
Bring milk and pistachio mixture to a boil in a heavy bottomed large saucepan;add almond extract.
Combine egg yolk s and remaining sugar and whisk to blend . slowly add to the pistachio mixture.
Cook over low heat until custard thickens and leaves a path on back of the spoon when finger is drawn across, stirring constantly, about 10 minutes. (DO NOT BOIL) ; strain into large bowl. Chill about 3 hours.
Stir whipping cream and chopped nuts into custard. Process mixture in ice cram maker according to manufacturer's instructions.
Note: if you like a little salty with your sweet- add a few salted pistachios.