So this isn't authentic by any means and, for being Cajun, it isn't particularly spicy. However, I incorporated the holy trinity to give this much more flavor than any Midwestern pot roast I grew up with in the Midwest.
Start with a rub. I used salt, white pepper, black pepper, cayenne pepper, nutmeg, and allspice. (More of the first half of list, less of the second half of the list.) Apply to a chuck roast. (I didn't remove the fattiest parts of the roast, but probably should have in hindsight.) Put roast in the crock pot.
Next, chop up two onions, a green bell pepper, and three ribs of celery. Spread across the top of the roast. Mince two cloves of garlic and also place on top. Drop in a bay leaf or two. Then, dump in a can of diced tomatoes. Finally, pour in some red wine and beef stock (lift the roast to let some liquid get underneath). Then, let the crock pot work its magic. I had mine on high for 4 hours and then switched to warm for another hour. It was very tender and fell apart pretty easily, but I think I let it cook just a smidge too long (my timing got off a little waiting for the potatoes.
The end product was really good (I ate mine after covering it with copious amounts of the au jus and chopped veggies left behind in the slow cooker), and it shall be made again.