When did the dish now called cassoulet take its current form and name, given that its own popular 1355 siege-of-Castelnaudary origin story is directly contradicted by the historical record?

Wikipedia's article on cassoulet reports the popular tradition that cassoulet was invented in 1355 during a siege of Castelnaudary, then states plainly that in historical fact there was no siege and the Black Prince sacked and burned the town instead. The same article dates the term cassoulet itself to no earlier than the 19th century per the Dictionnaire de l'Academie francaise, with only the vague label medieval estouffet for an earlier related dish. No source bridges the medieval estouffet and the 19th-century named cassoulet, so origin-start-year and origin-end-year are left unfilled rather than built on the disproven 1355 legend.