Place water in large saucepan, add broccoli and bring to the boil. Reduce heat and simmer for 8-10 minutes, until the broccoli is almost cooked but still crunchy. Drain and set aside.
Place the Knorr Vegetable Stock Pot, milk, mayonnaise, eggs and two thirds of the grated cheese in a medium size pan over very gentle heat. Stir continuously. Remove from heat once the cheese melts. Add in the broccoli and turn with a spoon until broccoli is covered with the mixture then pour into a large oven proof dish. Sprinkle with remaining cheese and breadcrumbs and bake for 15-20 minutes.