Season the plaice fillets with salt and pepper and turn them in flour. Place in a lightly greased baking dish. Clean and halve the mushrooms. Spread over the fillets. Now stir in the cream with the vegetable stock, pepper, chopped parsley and a little thyme. Pour all of this over the plaice and sprinkle with the grated cheese. In the oven at 160 ° C for approx. 20-25 minutes.