Bring a large pan of salted water to the boil and cook the pasta until al dente. Reserve a mug of the pasta water before draining.
Meanwhile, heat the olive oil in a large frying pan over a medium-high heat. Add the sausage meat, breaking it into small chunks with a wooden spoon. Leave it to brown well between stirring so you get plenty of crispy caramelised bits. Cook until golden.
Stir in the garlic and the dried thyme and cook for 30 seconds until fragrant.
Pour in the chicken stock, scraping up all the browned bits from the bottom of the pan. Simmer for 2 minutes.
Stir through the mascarpone, Parmesan, and Dijon mustard. Simmer gently for 2 to 3 minutes until smooth and silky. Add the chopped parsley and stir well.
Add the cooked pasta and toss everything together until coated in the sauce. If needed, loosen with a splash of the reserved pasta water until glossy.
Finish with plenty of black pepper, and an extra grating of Parmesan before serving.