STEP 1:
Thaw the Athens Phyllo Dough Shells and set aside until ready to fill. Grind pistachios in food processor until ground. Add water & pulse to form a paste.
STEP 2:
Whisk egg yolks, sugar, salt & cornstarch. On the stove, bring milk & butter to a simmer & slowly stream milk over egg mixture, while whisking.
STEP 3:
Return the mixture to the stove & whisk until the first bubble pops. Whisk for 1 more minute, remove from heat & pour through a sieve into a bowl.