We wrote the first draft in about nine weeks. Nine weeks of gloriously long phone calls, in which we would read each other what we'd written, and try to make the other one laugh. We'd plot, delightedly, and then hurry off the phone, determined to get to the next good bit before the other one could. We'd rewrite each other, footnote each other's pages, sometimes even footnote each other's footnotes.
Good Omens: How Neil Gaiman and Terry Pratchett wrote a book (2014)