Heat the oil in a large frying pan. Add the chicken and broccoli and cook until the chicken is golden all over – about 10 minutes.
Add the pasta sauce, parsley and spinach and simmer for 2-3 minutes until the chicken is cooked through with no pink remaining. Tip into a 1.5-litre ovenproof dish.
Meanwhile, preheat the grill to high. Cook the mash in the microwave to pack instructions, then spoon it over the chicken filling. Sprinkle the cheese over the top then put under the grill for 5-8 minutes, until the cheese is melted and golden.