Drop the rotini into the pot of boiling water. Remove the sausages from the pan and cut them into 1/2 cm rings. Return them to the pan along with the apples, shallot, garlic, and a splash of extra virgin olive oil. Fry until the sausages are caramelized and the apples softened but not mushy, about 5 or 6 minutes. Add a couple of pinches of salt and several grinds of freshly cracked black pepper.