Cook the brown rice according to directions. Sprinkle the chicken breasts with plenty of salt from all sides and let sit for at least 20 minutes. This works like brining and will make for tender chicken.
Melt the butter in a pan. Remove 2 tablespoons and set aside.
Cook the onion and garlic slices in melted butter on low heat until caramelized (about 20 minutes).
Bring broth to a boil and add cauliflower florets. Cook for 7-10 minutes until tender. Remove cauliflower with a slotted spoon to reserve the broth and add to a blender. Add caramelized onions and garlic, 1/2 cup of the broth, milk and seasonings. Blend everything into a very smooth sauce. Add more broth if necessary.
Preheat oven to 350 F. Grease a casserole dish (9x13 inches) and spread the cooked rice over the bottom.
Return the remaining broth to a boil. Blanch the broccoli florets for 1 minute until they turn bright green. Add the cauliflower to the casserole.
Heat 1 tablespoon of the butter in the frying pan. Cut the chicken into bite-sized pieces and quickly brown them from all sides. Add chicken to the casserole dish.
Pour the cauliflower sauce over the rice, broccoli and chicken. Sprinkle with grated cheese. Combine last tablespoon of melted butter with All-Bran Buds and spread over the top of the casserole. Bake for about 30 minutes for everything to heat through. The cheese should be bubbly and the All-Bran topping crispy.