Bring a large pot of salted water to the boil, boil the broccoli and cauliflower for 5-7 minutes, drain and set aside.
Put the vegetables into an oven proof dish.
Mix the Bisto Gravy Brown Onion and water together, and place in a small pot. Bring to a gentle simmer, and simmer for 5 minutes. Pour the gravy over the veggies and top with cheese.