Bake the chestnuts for 20 minutes at 170 ° C, then peel and chop.
Bring the water to the boil and add salt. Cook the pasta as usual.
Bring the crumbled chestnuts to the boil with a little water, add the onion, apple and cream and cook while the pasta is cooking. At the end, cut the chestnuts with a fork (optional: puree), season to taste with pepper and salt.
Drain and drain the pasta. Arrange with the sauce and serve immediately.
Puree makes the sauce creamier, personally I prefer a thinner sauce with sticks of chestnuts. Optionally, the cream can be replaced.
The chestnuts may already have become dry (hard) - they become soft again when they are cooked.