Cut potatoes into slices. Clean broccoli, rinse and cut into bite-sized pieces. Cut tomatoes into eighths. Grease a gratin dish with butter. Spread potato slices and vegetables evenly in the dish.
Mix processed cheese with egg yolk and whipped cream, season with salt, pepper and a pinch of nutmeg. Rinse kitchen herbs, spin dry or drain and chop finely. Add the herbs to the sauce and pour over the vegetables. Bake the casserole in a heated oven at 220 °C for about 10-15 minutes.
Our tip: If you like to cook with fresh herbs, it is best to get kitchen herbs in pots – so you always have everything ready!