Grate the orange zest, grind finely with the peppercorns and pine nuts using a pestle and mortar, mix with the cheese, season with salt.
Spoon the filling into a piping bag with a smooth nozzle (approx. 1 cm in diameter). Unroll one section of pasta dough, cut in half lengthwise.
Pipe 1/4 of the filling along the long edge of one strip of dough, leaving a free edge of approx. 1 cm. Brush the other side of the dough with egg white and fold it over the filling.
Press firmly along the long edge, pressing out any trapped air.
Use the sides of your hands to divide the Agnolotti, leaving a gap of approx. 4.5 cm between each pocket of filling.
Separate the Agnolotti using a wheeled pasta cutter.
Repeat this step three more times. Cook the Agnolotti in a large pan in just-boiling salted water for approx. 5 mins., drain.
Cut the leek in half lengthways, cut into pieces approx. 6 cm long. Heat the butter in a frying pan.
Add the leek and sauté for approx. 5 mins. Pour in the wine, bring to the boil, cover and simmer for approx. 5 mins. until soft, season.
Thinly peel the orange zest, cut into thin strips. Heat the butter. Add the sage leaves, fry for approx. 2 mins. until crispy. Add the orange zest.