Absolutely. Make and assemble the chicken broccoli divan up to adding the sauce on top of the chicken. Then wrap the dish in plastic wrap and aluminum foil, and freeze for up to three months. When ready to serve, let it defrost in the fridge for 24 hours. Then top the casserole with the cheese and breadcrumbs and bake for an hour. When cooking from cold, the casserole will need more time in the oven to come to temperature. Cover the dish lightly with foil if the breadcrumbs start to get too browned.