Preheat the oven to 200°C.
Place the squash, sweet potato, 2 tbsp oil, sage, garlic and half of the pancetta on a baking tray and mix to coat.
Roast in the oven for 20 to 30 minutes until beginning to brown.
Meanwhile, melt a knob of butter in a saucepan with the remaining oil and sweat the onion until translucent. Add the remaining pancetta and cook until browned.
Add the wine and reduce slightly before adding the barley, chicken stock and Parmigiano Reggiano rind.
Simmer, stirring occasionally, for 30 minutes. Add more stock if necessary.
Add the roasted vegetables and pancetta (reserving some for serving) and cook for a further 10 minutes until the barley is cooked through.
Remove from the heat, remove the rind and stir through the crème fraîche, grated Parmigiano Reggiano and season to taste.
Serve with the reserved roasted vegetables and pancetta, extra Parmigiano and sage.