2) Whilst the pasta is cooking, heat the oil and butter together in a large frying pan. Add the spring onions and the roasted garlic cloves and saute for 3 minutes, until the spring onions are soft. Add the beer and bring to a simmer. Add clams, cover and simmer for about 5 minutes, until shells open.
3) Using tongs, remove 12 clams and reserve for another meal. Drain the pasta, reserving 125ml of the pasta cooking water, and add to the clams. If the sauce need "loosening", add the reserved pasta water and simmer for about 1 minute to heat through.
4) Remove from heat and top with parsley and Parmesan and serve with a dressed, mixed green salad, if required.