Fry a chopped onion slowly until soft and golden – this is easiest by putting a lid on the pan and cooking over a low heat covered,
for about 10-12 minutes, stirring from time to time. Skin pork sausages and break into small balls, then, when the onions are caramelized,
add the sausage balls to the pan and fry for 10 minutes or so until browned and cooked through. Stir in a dollop (say a Tbs) of smooth Dijon mustard
and a dollop of grainy mustard, together with 200ml of double cream. Mix well, season with a little sea salt and freshly-ground black pepper
and keep warm. Meanwhile, cook pasta shells in boiling water until al dente, about 18 minutes, drain and stir into the sausage mixture.
Garnish with chopped parsley and grated parmesan and serve in warm bowls.