That base is jammed full of chopped pecans, but the real secret ingredient is a dollop of sour cream. The tart dairy works twofold: first, helping to prevent crystallization, and second, keeping the pie from becoming overly sweet. A bigger dollop of sour cream goes into the whipped topping, giving it noticeable tang. This is another point of flavor balance, but it also stabilizes it, so that it doesn't weep or dissolve on your Thanksgiving buffet.
I won't pretend that these are the height of Italian fashion, but style is eternal as is the childish joy of a bright yellow frozen lemon. You could, of course, buy in lemon sorbet instead, and use the flesh from the lemon shells for cocktails or lemonade (and/or freeze the juice for future use), but this really is such an easy make-ahead dessert that I urge you to give it a go.