Preheat the oven to 180°C
Place the prepared beetroot into a roasting dish, add the honey, 2 tablespoons of oil, chilly flakes and a little salt, mix it all together so the beetroot in nicely coated. Place it in the oven and cook for 40 minutes until the beetroot is soft and slightly charred.
In a medium pan at the rest of the oil and then cook the onions until soft.
Bring a medium pot of salted water to the boil.
Cook the pasta as per the instructions but remove it for the water 1 to 2 minutes before the pasta is ready (save a bit of the water).
Once the beetroot is cooked, blitz it up with a hand blender (making sure you keep all the juices), add the mascarpone and 2 tablespoons of the pasta water and blitz it again so it is all mixed together.
Add the beetroot mixture to the pan with the onion and warm it up on a medium heat, add the cooked pasta and finish off cooking the pasta in the pan with the beetroot mixture, slowly mixing and incorporating the parmesan cheese (if it is looking a bit dry add a bit of the pasta water) season with salt and pepper.
When the pasta is finished and ready to serve sprinkle over the parsley and the walnuts.