Wash and dry chicken. Cut into pieces which are a little bigger than bite size. Add all spices and mix.
Toss chicken into large plastic sealed bag. Add one tablespoon olive oil and one tablespoon Worcestershire sauce. Seal bag and work it with your hands, ensuring all the chicken is coated. Marinate in fridge for at least 3 hours.
Chop broccoli, celery and onion into bite-size pieces. Mince jalapeno. Keep jalapeno seeds and white veins if you want this spicy!
Chop cauliflower. In batches, pulse in blender or food processor until cauliflower resembles tiny pieces of rice.
Saute all veggies except for cauliflower, in 2 Tbs olive oil, for 10 minutes or until they are softened but not mushy. When done, transfer to a large bowl.
In same pan, saute cauliflower in 2 Tbs olive oil until just slightly browned.
Add cauliflower to bowl with sauteed veggies. Wipe pan clean of any leftover cauliflower bits.
In the same pan, saute chicken pieces in 2 Tbs olive oil (you may need to add more as you go) until outside of chicken is slightly browned, about 2-3 minutes each side. Don't cook chicken all the way through. Also, do this in batches to not overcrowd the chicken.
Add chicken to big bowl with veggies. Set heat under same pan to low and deglaze pan with the broth.
Add all sauce ingredients to the pan and stir to combine. At this point...preheat oven to 375. Cover pan and stir every few minutes until sauce is smooth.
Stir sauce every few minutes until it is smooth. Turn off heat.
In a separate, small saucepan, melt butter on low heat.
Add breadcrumbs and stir to coat them in butter. Leave heat on for about 30 seconds and then turn it off. You want the breadcrumbs coated in butter and just a tad crispy. Set to the side.
I opted to make this dish in 2 round pans (easier to store in fridge). Mix your chicken and veggies, and then pour into pan(s).
Equally distribute cheese sauce over the top. Use knife or spatula to cut into chicken and veggies, to ensure cheese has a place to seep into (but don't mix it all together).
Bake covered for 30 minutes.
After 30 minutes, take off tops and spread on the panko coating (I forgot to snap a pic when I did this so here is a pic right after I did this, and had already put chicken back in the oven). Bake UNCOVERED for 15-20 minutes until topping is browned.
Take out of the oven and leave partially uncovered; let stand for 15 minutes to cool. Enjoy!