Separate the eggs - reserving the whites for another use.
In a saucepan, whisk together the condensed milk, cream, milk, pistachio flavoring and vanilla. Place over medium heat. Set your timer for 10 minutes and whisk continuously.
Slowly add the egg yolks, one at a time. Continue to cook and whisk. Do not allow it to boil. Whisk the entire time. The mixture will thicken slightly.
After 10 minutes is complete, pour the custard into a large bowl, cover with plastic wrap and place it in the refrigerator. Refrigerate for at least four hours - the custard must be completely cooled.*
When you are ready to make the ice cream, prepare the machine. Pour the pistachio mixture into the ice cream maker. Process according to your manufacturer's instructions. Mine took about 40 minutes.
Shell and roughly chop the pistachios while the ice cream is processing. When the ice cream maker stops stir in the pistachio pieces.
Depending upon your machine you may need to freeze it longer, but why wait?!! We enjoy ours as soon as it's done!!
Store ice cream in a freezer-safe container.
Notes
Make sure the custard is completely cooled before processing it in the ice cream machine.
If you're short on time place the bowl of custard into a second bowl filled with ice water - then tuck it into the fridge. That will cool it more quickly.