Heat 2 tbls oil in a non-sticking pan and cook 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 tbls of oil , add chestnuts and bay leaf and toss for a minute. Set aside.
Melt 30 g (1 oz/ 2tbsp) of butter and the sugar in the same pan; add onion wedges and cook for 5-6 minutes until lightly caramelize; season with salt and pepper and add remaining butter.
In the meantime cook the Tortelloni according to package instructions and drain, reserving a ladle of the pasta cooking water. Add 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.