In your blender, soak pistachios in milk for 30 minutes.
Blend on high for 1-2 minutes.
Pour milk through a fine mesh strainer or a cheese cloth to separate pulp from milk.
In a heavy saucepan, pour all the milk except for 1/4 cup and heat.
Stir in sugar until completely dissolved then add vanilla.
In a cup mix the cornstarch and the remaining 1/4 cup of milk.
When there is no lumps, pour the cornstarch mixture over the warm milk in the saucepan.
Keep stirring until the mixture gets bubbly and thick, remove from heat.
Pour pudding into individual serving bowls, cover with plastic wrap and chill until ready to serve.
Garnish with more pistachios and serve.