Ingredients

• 1 cup key lime juice (more or less to taste)
• 1 cup water
• 1/4 cup vodka
• 1/4 cup vanilla sugar (more or less to taste)
• 1/2 cup heavy cream

Procedure

Bring the key lime juice, water, and vodka to a boil, and add the vanilla sugar.  You could add the vodka later if you wanted to keep the alcohol content.  Once the sugar has dissolved, take the mixture off the stove to cool.

Add the cream (and the vodka if you want to retain the alcohol) and decant into a brownie baking dish.  Place in the freezer, and scrape with a fork once an hour for 4 hours or until flakey and frozen in little key lime pie crystals.