Remove the skins from the sausages and form each sausage into 4 balls.
Heat the oil in a frying pan and cook the sausage balls for about 8 - 10 minutes, stirring until just browned.
Add the garlic, passata and 1 tbsp of the thyme to the pan and cook for 4 - 5 minutes more. Meanwhile cook the spaghetti as instructed on pack.
Turn off the heat and stir the mascarpone into the tomato sauce, toss in the pasta and mix well. Chop the remaining thyme leaves and mix with the parmesan, scatter over to serve.