In mushrooms, remove the legs and part of the pulp (it is convenient to use a noisette, but you can also use a spoon). Do not use the legs, and chop the pulp with a knife.
Finely chop the onion and fry it until golden brown.
Add the chopped mushrooms.
Fry for 2-3 minutes.
Add the chopped chicken breast and stir.
Fry for another 3 minutes.
Add the chopped canned pineapples and mix.
Warm up for 1 min.
Add the chopped canned pineapples and mix.
Warm up for 1 min.
Fill the mushroom caps with minced meat.
Put the mushrooms in a form slightly greased with vegetable oil.
Spread the grated cheese on top, pressing it down.
Place in a preheated 180*C oven for 10-15 minutes.