Whisk the eggs with cream or milk and season with salt, pepper and Provence herbs. Cut the onion and apple into wedges, slice the mushrooms.
Heat some oil in a small pan, add onion and apple and season well with sugar and chilli. Fry until light brown, then add the mushrooms and cook for 5 minutes over low heat.
Crumble the feta over the mixture and pour the egg mixture over it. Now simply let it set with the lid closed until the surface of the omelette is firm.
Tip: You can of course leave out individual ingredients, but I just had everything in the house and it tastes very tasty in this combination.