In a medium saucepan, combine the milk, sugar, cornstarch, and salt.
Whisk the mixture over medium heat until it begins to thicken.
Stir in the ground pistachios and continue cooking for another 2 minutes.
Remove from heat and add the vanilla extract and butter.
Mix until the butter is fully melted and incorporated.
Pour the pudding into serving dishes or bowls.
Allow it to cool at room temperature for about 30 minutes.
Refrigerate for at least 2 hours to set properly.
Before serving, top with whipped cream.
Garnish with chopped pistachios for an extra crunch.