For the yellow omelette, peel and finely dice the onion. Whisk 4 eggs with cream. Season with salt and pepper. Heat 1 tablespoon of oil in a coated pan (20 cm Ø) with lid. Fry the onion until transparent.
Stir in whisked eggs. Covered and let stand for 6-8 minutes at low heat. Slide the omelette onto a plate. Wipe the pan with kitchen paper.
For the green omelette, grate parmesan. Clean and wash the spinach and drain well. Wash the herbs, shake dry and chop finely. Whisk 4 eggs, season with salt, pepper and nutmeg. Heat 1 tablespoon of oil in a frying pan.
Add the spinach and herbs and let them collapse for about 2 minutes. Stir in whisked eggs and sprinkle Parmesan cheese over it. Cover and let it simmer at low heat for 6-8 minutes. Slide onto the yellow omelette.
Wipe the pan again with kitchen paper.
For the red omelette, wash and quarter the tomatoes. Whisk 4 eggs with tomato paste. Season with salt and pepper. Heat 1 tablespoon of oil in a frying pan. Sauté the tomatoes briefly. Stir in whisked eggs.
Crumble the goat's cheese evenly over it. Cover and let it stand for 6-8 minutes at low heat, then slide it onto the green omelette.
Wrap the omelette cake first in parchment paper and then in aluminium foil. Place in a cool place for at least 1 hour, weighted down with a board. Serve with pesto.