Master mixologist erick castro of san diegos polite provisions tinkered with the typical pia colada recipe, adding ever-greater shares of green chartreuse to get more of its complex, herbaceous flavor. Eventually, he ditched the rum entirely and maxed-out the chartreuse, tinkering with the recipe until he landed on this recipe for the pia verde. Its difficult to specify how much ice should go into a blended drink; much depends on the type of ice you use, the style of blender, and so on. Start with about a cupful of ice for each serving, and add more ice, a half-cup at a time, until youve achieved a thick mixture that cant quite hold a spoon upright.