Clean, wash and cut the leek into rings. Dice the ham. Cook pasta in boiling salted water for about 12 minutes. In the meantime cook leek in boiling salted water for about 4 minutes. Melt the fat in a pot, dust with flour, sweat on and deglaze with stock and cream. Stir mustard into the sauce and season with salt, pepper and sugar.
Drain the leek on a sieve. Stir leek and ham into the sauce. Drain the noodles, quench briefly and allow to drain. Arrange noodles and sauce on a plate and serve sprinkled with cress and pepper. Garnish with parsley as desired