Knead the flour, eggs, cocoa and semolina into a smooth dough. If necessary, add a little water. Wrap the dough in cling film and let it rest for 2 hours in the refrigerator.
For the filling, roughly chop the couverture and melt it in a hot water bath. Mix the ricotta, lemon juice, vanilla, 2 tablespoons sugar and the egg yolks until creamy, fold in the couverture.
Roll out the cooled dough thinly on a lightly floured surface. Cut out circles with a glass or a round cookie cutter. Put some of the ricotta filling in the center of the circles and brush all around with a little whisked egg yolk. Now just fold it up and press the edges together with a fork or your finger.
For the cherry ragout, caramelize the sugar in a saucepan. Deglaze with port wine, red wine and cherry juice. Reduce by half over high heat. Take off the stove. Gradually stir the butter in pieces into the sauce. Mix in the cherries, keep warm.
Bring water to the boil with plenty of sugar in a saucepan. Cook the ravioli in it for about 3 minutes. Arrange with the cherry ragout on plates and serve warm.