Combine the Ricotta and all the ingredients up to and including pepper. Halve 1 section of dough crossways, halve the Ricotta mixture. Divide 12 portions (each approx. 1/2 tbsp) onto 1 section of dough. Coat the 2nd half of the dough with a little egg white, lay over the filling, press down lightly and press out the trapped air. Separate the ravioli from each other with a sharp knife, press the edges down firmly. Repeat with the remaining dough and remaining mixture. Steep the ravioli in batches in just-boiling salted water for approx. 5 mins., drain, and keep warm.
Heat the butter and sauté the onion, asparagus and morels for approx. 5 mins. Add the stock and bring to the boil. Simmer the vegetables for approx. 10 mins. until almost soft, season. Serve the ravioli with the vegetables and cooking juices. Top each serving with a knob of butter.