Fillet the soles and form rolls that hold with a toothpick. Place them in a baking dish greased with butter, add salt and a spoon of butter on top. Put in hot oven 200 °C  for 5 minutes. Remove the paupiettes to a serving dish and reduce the remaining broth to half. We have already made a Hollandaise sauce, to which we will be adding gradually the reduction of cava. Cover the sole with the hollandaise sauce and garnish with the trout roe. Serve.