Heat 2 tbsp of olive oil in a non-stick pan and cook the butternut squash slices for 2-3 minutes until lightly golden. Season with salt and pepper and set aside. In the same pan add 2 more tbsp of oil, add the chestnuts and the bay leaf and toss for a minute. Set aside.
Melt the sugar and half the butter in the same pan; add the onion wedges and cook for 5-6 minutes until lightly caramelised; season with salt and pepper and add the remaining butter.
In the meantime cook the tortelloni according to the pack instructions and drain, reserving a ladle of the pasta cooking water. Add the tortelloni, butternut squash and chestnuts to the pan, mix them with caramelized onions and a few spoons of pasta water and toss to combine. Serve immediately.