Place the broccoli and cauliflower into a pot with a little water on the stove, and bring to a boil. Blanch for 5 minutes, and then rinse and drain.
Place the olive oil in a high sided skillet over medium-high heat on the stove, and add the chicken to the heated skillet as well as salt and pepper to taste.
Pour the chicken and sauce mixture over the vegetables in the casserole dish, and toss to combine.