Break the cauliflower into flowerets and cook in boiling salted water until just tender for about 10 minutes.
Drain and keep aside.
Grate the cheese and slice the tomato into thin rounds.
Keep aside 50 ml of cold milk and bring the rest of the milk to boil.
Mix the corn flour with cold milk. Add to the boiling milk, stirring as it thickens.
Add the grated cheese and mix well. Turn off the heat and cool for 15 minutes.
Add the egg/egg yolks to the cheese sauce together with 1 teaspoon of dried herbs, 1 teaspoon of dry mustard powder, 1 teaspoon of pepper powder and salt to taste.
Add the cooked cauliflower florets into the cheese sauce and pour into a ovenproof dish.
Arrange the sliced tomatoes over the cauliflower cheese (optional). Brush tomatoes with a little olive oil or butter.