Put the crumble aside until needed later on. Slice the merguez sausages up and add them together with half of the unsalted butter to a medium saucepan. Gently bake the sausages for some minutes until cooked through.
Stir well and cook for 2 minutes. Keep the cabbage crunchy! Season with a pinch of pepper and salt. Then take the cabbage off the heat. Once the pasta is cooked, drain it and add it back to the pan together with the walnut sauce, the merguez crumble and the cooked cabbage.
Stir all the ingredients well. Then check the seasoning and add extra pepper or salt to taste if necessary. Transfer the pasta onto plates (sprinkle with grated parmesan cheese if you like) and serve hot.