Fill a large lidded pot with water and bring it to a boil. Remove the heads from Shrimp (2.5 pound) and place them in a bowl.
When the water is boiling, toss in the shrimp heads, Salt (2 teaspoon) and Fresh Parsley (1 handful). Give it a stir and return to a boil.
Cover partially with a lid and let simmer for 30 minutes, skimming off the foam halfway through.
Drain and discard the solids. Allow the stock to cool before transferring to ziploc bags. Store in the freezer.