Prepare the dough. Pour flour into a mound on the table or in a deep bowl. Make a well in it and put eggs and salt in it. Knead the dough thoroughly until it is smooth and elastic. Put the finished dough in the refrigerator for 30 minutes.
Make the mushroom filling. Heat the vegetable oil in a frying pan. Add the chopped mushrooms and onion. Fry for about 4 minutes. Add a spoonful of processed cheese, stir. Simmer for another 1 minute.
Make cheese ravioli. Take chilled dough. Divide it into 2 parts, roll each of them with a rolling pin to a thickness of 2 mm. Using a knife, cut the layers into even strips 5 cm wide. Set aside half of them, and put the mushroom filling on the other half. Cover the strips with the filling with the dough you set aside earlier. Cut squares with a sharp knife so that the filling is exactly in the middle of each ravioli. Press the edges well. Leave the mushroom ravioli for 10 minutes.
Prepare the cream sauce. Pour the cream into a saucepan or a thick-bottomed pan and add the processed cheese, salt and pepper. Place the container on medium heat. Stir until the sauce thickens.
Pour water into a saucepan and bring to a boil. Throw the ravioli into the boiling water and cook for 3-4 minutes.