
Prepare the filling. Heat olive oil in a frying pan. Fry the onion and mushrooms until all the liquid from the champignons has evaporated and the onion has become soft. Transfer the frying mixture to a bowl. Add processed cheese, dill, and mayonnaise. Mix everything well.

Bake the peppers. Fill the pepper halves with the mushroom filling. Sprinkle a little hard cheese on top. Bake in the oven at 180 degrees for 17 minutes.