Preheat the oven to 400 F/ 200 C/ gas mark 6. Whilst the vegetables are in the oven boil the pasta in salted water according to package instructions. Drain and reserve at least 1/2 cup of the water from cooking.
Peel the beetroot, cut into wedges and place in your oven dish. Add the onion and garlic, season and drizzle with 2 tablespoons of oil. Bake for 30 minutes or until the beetroot is tender. Halfway through remove the garlic from the oven and stir the beets and onion. Puree the vegetables along with the garlic, fromage frais and 1/3 cup of the water from cooking the pasta (you can add more later if needed). Season to taste and set aside.
Combine the beetroot sauce with the pasta and grated parmesan, stir, adjust the seasoning (and add more water if needed) and serve.
The sauce: You could use (low fat) creme fraiche instead of the fromage frais if you prefer. Add the water gradually to get the consistency you want.
The pasta: Use any pasta shapes you like.
Best served immediately. Leftovers can be refrigerated for up to 3 days. You may have to add a splash of water (and adjust the seasoning) when reheating the pasta.
Freeze individual portions in an airtight container for up to 3 months. Alternatively freeze just the sauce.