melt butter in a pan, add a spinach, cover, and cook for 2 to 3 minutes on medium high heat until wilted. Set aside to cool. Cook peas and beans in boiling water for 5 minutes, until tender. Drain and set aside.
Process spinach and the creme fraiche in a food processor until smooth. Return puree to the pan, stir in peas and the beans. Stir in spring onions and parsley. Season and add half the parmesan. Keep warm over a low heat.
Cook pasta in a large pan of boiling water, until al dente. Drain, toss with spinach sauce. Sprinkle with the remaining Parmesan.