How to make
Peel and slice the potatoes (5 mm thick). Arrange them in one layer in a baking pan greased with olive oil - they may overlap slightly.
Sprinkle them with salt, black pepper and a little more olive oil and bake them for 20 minutes in a preheated oven at 370°F (190 degrees). They should not be baked too much and shouldn't become too crunchy.
Meanwhile, boil the cauliflower in salted water briefly and leave it al dente. Strain and allow it to cool and you can pour cold water to stop the cooking process.
Arrange the cauliflower around the walls of the baking pan on top of the potatoes and in the center place the tomato, cut into thin circles. Sprinkle with more olive oil and salt and put it in the preheated oven at 390°F (200 degrees) for 15 minutes.
For the topping, beat the eggs with two pinches of salt and add the cream, mixed herbs and salt, more black pepper, if desired and lemon juice.
Stir until a homogeneous mixture is obtained and pour it over the dish. Place it back into the oven for another 5-6 minutes or until it starts to aquire an appetizing color.
Finally, sprinkle it with grated yellow cheese or Emmental and bake it briefly.
Sprinkle it with fresh parsley, if desired.
The Gratin with Potatoes, Cauliflower and Tomatoes is ready.