for the pasta, sift the flour, cocoa powder and salt onto a clean work surface preferably made of wood. Make a well in the center. Pour the beaten eggs into the well. Use your fingertips two gradually incorporate the eggs into the flour. Take care not to break the wall of flour or the eggs will run. Gather the dough up into a ball. Knead the dough until smooth and silky, about 20 minutes.
Wrap the dough in plastic wrap and let rest for 30 minutes. Divide the dough into pieces. Roll a piece of dough through a pasta machine at the thickest setting. Continue rolling the dough through the machine, reducing the thickness setting one notch at a time down to the required thickness. Sprinkle with semolina and cover with a clean dry cloth. Set the machine to cut to 1/4 inch wide and run each sheet through. Cook the pasta in a large pot of salted boiling water until al dente.
Sauce: while the pasta is cooking, melt the butter and sage in a small pan. Drain the pasta and toss gently with the butter and sage. Take a large pasta fork and wrap about a quarter of the pasta around it to make a nest. Place three mozzarella is in the center and season with freshly ground pink pepper. Repeat with the remaining pasta and mozzarella. Serve hot. Serves four.