Prepare a pasta dough using the flour, eggs, olive oil and a pinch of salt. Wrap in foil and let rest in the refrigerator for 30 minutes.
In the meantime, mix the mascarpone, parmesan, parsley, breadcrumbs, egg yolks and walnuts together and season with salt and pepper.
Roll out the dough. Place cams of the filling on the dough at a distance of 3 cm. Brush the gaps and edges with water or egg white. Place a second sheet of pastry on top, press down on the gaps and cut out the ravioli.
Put in boiling salted water and cook on low heat for 3-4 minutes.
Melt butter, sprinkle with coarsely chopped sage, season with salt and pepper. Briefly turn the ravioli in the butter, arrange and sprinkle with parmesan and serve decorated with a sage leaf each.