Stir in the Ricotta and remaining ingredients with the egg yolk, season.
Halve the pasta dough lengthways, coat 2 of the 4 dough strips with egg white. Halve the filling and divide 8 walnut-sized portions onto each dough strip. Lay the other two uncoated dough strips on top, press down lightly, pressing out the trapped air. Separate the ravioli with a pastry wheel. Melt the butter and sauté the sage. Steep the ravioli in batches in just-boiling salted water for approx. 5 mins., drain, arrange on two plates and top with the sage butter.