Boil the pasta according to the instructions on the package. Put aside a cupful of the cooking water, then drain the pasta and keep it warm in the pan under a lid.
Meanwhile, pour hot water over the spinach. When the leaves wilted, drain and squeeze the water out. Chop it up roughly.
Dry-fry the pine nuts in a frying pan, set aside.
Heat the oil in the frying pan. Thinly slice the garlic and fry it until light brown in the heated oil.
Add the vinegar, let it bubble for 1 minute. Stir in the spinach and heat through.
Add the pasta and pine nuts, mix thoroughly. Add enough of the pasta cooking water to make a smooth, loose consistency.
Just before serving sprinkle with chilli flakes and cheese - but either or both can be left out if you wish.