There is no original recipe, the dish evolved throughout the years and depending where you go, the recipes are different. Sure, you have Castelnaudary, Toulouse and Carcassone, but what does that make of Narbonne? Montauban? Pau? Mazères? And many others... all those cities had their own version of the dish.
One thing that's widely known is that the original Cassoulet was not made with beans, which were only introduced in France after Cassoulet was invented. Instead, the original Cassoulet was made with fava beans. Then a bunch of whatever meats were leftover.
But leaving "original" aside, It's going to be extremely difficult to make a typical cassoulet in the US unless you have access to French meats, or can make your own sausages. Typical cassoulets contain "Saucisson a l'ail" and "Saucisse de Toulouse" which I've never seen here in Los Angeles, not even in French specialty stores. As for chopped up fried bacon, sorry mgchef but that's anything but original or typical of a French cassoulet. Big thick pieces of pork belly cooked in the sauce, now that's more typical.
Also to note is that cassoulet, like paella, takes its name from the dish it's cooked in, the cassole. It's a flat bottom conical vessel made from clay and varnished, kinda like a tajine bottom but much smaller and deeper.
Edited by French Fries - 3/31/10 at 9:13pm