Season your chicken with the Cajun seasoning. Then dust each piece with flour.
Prep your veggies: dice the onion, green bell pepper, and celery. Mince the garlic.
Heat the olive oil in a cast iron pan (preferably) on med high. Once the pan is very hot, add the chicken and brown on both sides. It should only take 1-2 minutes on each side to brown the chicken.
Then add the bay leaf, diced onion, green bell pepper, celery, garlic, and chicken broth to the pan. Stir everything around, cover, and cook for 1 hour. Check and stir every 20 minutes or so and add a tiny bit of additional broth if you feel there is not enough gravy.
After the hour, taste and adjust the seasoning by adding salt, pepper, and additional Cajun seasoning to your tastes.