I once spent two hours thinking about how to recursively assemble a tree structure from the database in a way that the JS presentation library wanted the data, then finally I wrote 2 lines of code.

Definitely my most cherished code.

Hah, this is something I've done when trying getting data from a government agency that can't run or write code themselves. It's usually in some awkward meta-adversarial context and they tend to be fearful of macros and such, but it's possible to get around that fear by writing everything in excel functions.

Sometimes those damn excel sheets take hours and hours to make even though it would otherwise take me less than a minute to write in SQL or unix. But it pays off every time and pushes a clear message that they can do better.