Pasta with Potatoes and Sausage (Pasta e Patate con Salsiccia)

Ingredients

Scrub and cut the potatoes into 1cm cubes, and finely chop the leek (reserving any scraps for stock). In a large, heavy-based pot set over medium-low heat, fry the leek in four tablespoons of olive oil with a pinch of salt until it begins to soften.
Add the potatoes to the pot, stirring until every cube is coated and glistening with oil, then add the bay leaf and 1.2 litres of water. Bring to a boil, then reduce heat and simmer gently for 30 minutes.
While the soup is simmering, gently fry the garlic in a frying pan along with the red chilli flakes and the remaining two tablespoons of olive oil. Squeeze the sausage meat from its casing, crumble it into the pan, and cook until browned all over. Transfer the cooked sausage into the soup pot.
After the sausage has simmered in the soup for 10 minutes, increase the heat to bring the liquid to a steady boil. Add the pasta and cook until al dente, adding a little extra water if needed.
Remove from the heat and finish by stirring in the grated Pecorino cheese and plenty of freshly ground black pepper.